Gemini: A UK Twin Birth Cohort With a Focus on Early Childhood Weight Trajectories, Appetite and the Family Environment

Early childhood appetitive traits and eating disorder symptoms in adolescence: a 10-year longitudinal follow-up study in the Netherlands and the UK

BACKGROUND

Obesity and eating disorders commonly co-occur and might share common risk factors. Appetite avidity is an established neurobehavioural risk factor for obesity from early life, but the role of appetite in eating disorder susceptibility is unclear. We aimed to examine longitudinal associations between appetitive traits in early childhood and eating disorder symptoms in adolescence.

METHODS

In this longitudinal cohort study, we used data from Generation R (based in Rotterdam, the Netherlands) and Gemini (based in England and Wales). Appetitive traits at age 4-5 years were measured using the parent-reported Child Eating Behaviour Questionnaire. At age 12-14 years, adolescents self-reported on overeating eating disorder symptoms (binge eating symptoms, uncontrolled eating, and emotional eating) and restrictive eating disorder symptoms (compensatory behaviours and restrained eating). Missing data on covariates were imputed using Multivariate Imputation via Chained Equations. Ordinal and binary logistic regressions were performed in each cohort separately and adjusted for confounders. Pooled results were obtained by meta-analyses. Sensitivity analyses were performed on complete cases using inverse probability weighting.

FINDINGS

The final study sample included 2801 participants from Generation R and 869 participants from Gemini. Pooled findings after meta-analyses showed that higher food responsiveness in early childhood increased the odds of binge eating symptoms (odds ratio [OR]pooled 1·47, 95% CI 1·26-1·72), uncontrolled eating (1·33, 1·21-1·46), emotional eating (1·26, 1·13-1·41), restrained eating (1·16, 1·06-1·27), and compensatory behaviours (1·18, 1·08-1·30) in adolescence. Greater emotional overeating in early childhood increased the odds of compensatory behaviours (1·18, 1·06-1·33). By contrast, greater satiety responsiveness in early childhood decreased the odds of compensatory behaviours in adolescence (0·89, 0·81-0·99) and uncontrolled eating (0·86, 0·78-0·95) in adolescence. Slower eating in early childhood decreased the odds of compensatory behaviours (0·91, 0·84-0·99) and restrained eating (0·90, 0·83-0·98) in adolescence. No other associations were observed.

INTERPRETATION

In this study, higher food responsiveness in early childhood was associated with a higher likelihood of self-reported eating disorder symptoms in adolescence, whereas greater satiety sensitivity and slower eating were associated with a lower likelihood of some eating disorder symptoms. Appetitive traits in children might be early neurobehavioural risk factors for, or markers of, subsequent eating disorder symptoms.

FUNDING

MQ Mental Health Research, Rosetrees Trust, ZonMw.

Prospective associations between early childhood parental feeding practices and eating disorder symptoms and disordered eating behaviors in adolescence

OBJECTIVE

Nonresponsive parental feeding practices are associated with poorer appetite self-regulation in children. It is unknown whether this relationship extends beyond childhood to be prospectively associated with the onset of eating disorder (ED) symptoms in adolescence. This exploratory study therefore investigated prospective associations between early childhood parental feeding practices and adolescent ED symptoms and disordered eating behaviors.

METHODS

Data were from two population-based cohorts with harmonized measures: Generation R (Netherlands; n = 4900) and Gemini (UK; n = 2094). Parents self-reported their pressure to eat, restriction and instrumental feeding (i.e., using food as a reward) at child age 4-5 years. Adolescents self-reported their compensatory behaviors (e.g., fasting, purging), binge-eating symptoms, restrained eating, uncontrolled eating, and emotional eating at 12-14 years. Associations between feeding practices and ED symptoms were examined separately in each cohort using generalized linear models.

RESULTS

In Gemini, pressure to eat in early childhood was associated with adolescents engaging in compensatory behaviors. In Generation R, parental restriction was associated with adolescents engaging in compensatory behaviors, restrained eating, uncontrolled eating, and emotional eating. Instrumental feeding was associated with uncontrolled eating and emotional eating in Generation R.

DISCUSSION

Nonresponsive parental feeding practices were associated with a greater frequency of specific ED symptoms and disordered eating in adolescence, although effect sizes were small and findings were inconsistent between cohorts. Potentially, the cultural and developmental context in which child-parent feeding interactions occur is important for ED symptoms. Further replication studies are required to better understand parents' role in the development and maintenance of ED-related symptoms.

PUBLIC SIGNIFICANCE

Prospective research examining how early childhood parental feeding practices might contribute to adolescent ED symptoms is limited. In two population-based cohorts, nonresponsive feeding practices (restriction, instrumental feeding, pressure to eat) predicted increased frequency of some ED symptoms and disordered eating behaviors in adolescence, although associations were small and further replication is required. Findings support the promotion of responsive feeding practices, which may benefit young children's developing relationship with food.

Reciprocal associations between parental feeding practices and child eating behaviours from toddlerhood to early childhood: bivariate latent change analysis in the Gemini cohort

BACKGROUND

Parental feeding practices (PFPs) are a key component of a child's food environment. Parent-child feeding relationships are hypothesised to be bidirectional; however, to date, few large prospective studies have examined this, instead focussing on unidirectional relationships. As such, the direction of relationships between PFPs and children's eating behaviours remains unclear.

METHODS

Data were from Gemini, a population-based sample of children born in England and Wales in 2007. Children's eating behaviours and PFPs were measured at 15/16 months and 5 years using validated psychometric measures (n = 1,858 children). Bivariate Latent Change Score Modelling was used to examine the nature of relationships between PFPs and children's eating behaviours at 15/16 months and 5 years. Models were adjusted to account for clustering of twins within families and for sex of the child, socioeconomic status, gestational age and age of the child at measurement time points.

RESULTS

A reciprocal relationship was observed between instrumental feeding and emotional overeating, with greater instrumental feeding predicting greater increases in emotional overeating (β = .09; 0.03-0.15; p = .004) and vice versa (β = .09; 0.03-0.15; p = .005). Reciprocity was also observed between encouragement to eat nutritious foods and children's enjoyment of food, with greater encouragement predicting greater increases in enjoyment of food (β = .08; 0.02-0.13; p = .006) and vice versa (β = .07; 0.02-0.11; p = .003). Parent-child associations and child-parent associations were also observed.

CONCLUSION

These findings are consistent with the hypothesis that certain feeding practices are used as a 'natural' response to a child expressing a greater interest in and enthusiasm for food, but at the same time, such practices impact the development of eating behaviours by nurturing and encouraging the expression of higher emotional overeating and greater enjoyment of food in preschool years. The findings provide important insights into the PFPs and eating behaviour traits that could be targeted as part of a tailored feeding intervention to support parents of children during the preschool formative years.

Parental feeding practices as a response to child appetitive traits in toddlerhood and early childhood: a discordant twin analysis of the Gemini cohort

BACKGROUND

Parental feeding practices (PFPs) have been implicated in the development of children's eating behaviours. However, evidence suggests that feeding practices may also develop in response to their child's weight or emerging appetitive traits. We used the twin design to test the hypothesis that parents develop their feeding practices partly in response to their child's appetite.

METHODS

Data were from Gemini, a population-based cohort of 2402 British families with twins born in 2007. Psychometric measures of PFPs and appetite were completed by parents when their twins were 16-months and 5-years. Within-family analyses including all twins with available data in the sample (n = 1010-1858 pairs), examined if within-pair differences in PFPs were associated with differences in appetitive traits, controlling for differences in birth weight-SDS, early feeding method and child sex. In a subsample of twin pairs who were considerably discordant for appetitive traits by ≥ 1SD (n = 122-544 pairs), the direction and magnitude of within-pair differences in feeding practices was explored.

RESULTS

Within-family variation in parental feeding practices in toddlerhood and early childhood was low (discordance ranged from 0.1 to 6% of the sample), except for pressure to eat (toddlerhood: 19%; early childhood: 32%). Within-pair differences in all appetitive traits were associated with differential use of 'pressure to eat' at both 16-months and 5-years. In the subsample of twins most discordant for appetitive traits, parents used more pressure with the twin expressing lower food responsiveness, lower emotional overeating, lower food enjoyment, higher satiety responsiveness, slower speed of eating, higher emotional undereating and greater fussiness in toddlerhood and early childhood (p-values < 0.001). Effect sizes were small to large at 16-months (η²=0.02-0.09) and 5-years (η²=0.05-0.21).

CONCLUSION

Parents rarely varied their feeding practices between twins in toddlerhood and early childhood, except for pressure. Parents exerted greater pressure on their twin who expressed a poorer appetite compared to their co-twin, suggesting that parents develop a pressuring feeding style when their child expresses a poorer appetite or lower interest in, and enthusiasm for, eating. These findings could be used to guide interventions seeking to support parents in feeding their children in a way that nurtures the development of healthy eating behaviours.

Prospective associations between parental feeding practices used in toddlerhood and preschool children's appetite vary according to appetite avidity in toddlerhood

Parental feeding practices are a key modifiable component of children's food environments. Evidence suggests that certain feeding practices may differentially influence children's eating behaviour or weight, depending on the child's temperament (e.g. emotionality). Building on this work, we tested the hypothesis that feeding practices during toddlerhood influence children's developing eating behaviours differently, depending on their appetite avidity (which is characterised by a larger appetite and greater interest in food). Data were from Gemini, a population-based cohort of British twin children born in 2007. Parental feeding practices were assessed at 15-months, and child appetite at 15-months and 5-years, using validated psychometric measures (n = 1858 children). Complex samples general linear models examined prospective associations between PFPs at 15-months and child appetitive traits at 5-years, adjusting for clustering of twins within families and for the corresponding child appetitive trait at 15-months, difference in age between timepoints, child sex, gestational age, and socioeconomic status. Moderation analyses revealed that pressuring a child to eat led to greater increases in emotional overeating from 15-months to 5-years, only for children with high (1 SD above the mean: B = 0.13; SE± = 0.03,p < 0.001) or moderate emotional overeating (mean: B = 0.07 ± 0.03,p < 0.001) in toddlerhood. Greater covert restriction predicted greater reductions in emotional overeating and food responsiveness from 15-months to 5-years, only for children with high emotional overeating (1 SD above the mean: B = -0.06 ± 0.03,p = 0.03) and low food responsiveness (1 SD below the mean: B = -0.06 ± 0.03,p = 0.04) in toddlerhood. These findings are consistent with the hypothesis that children with a more avid appetite in toddlerhood are differentially affected by parental feeding practices; caregivers of toddlers may therefore benefit from feeding advice that is tailored to their child's unique appetite.

Associations between the home environment and childhood weight change: a cross-lagged panel analysis

BACKGROUND

The obesogenic quality of the home environment is hypothesised to play an important role in children's weight development but few prospective studies have investigated relationships between the home environment and adiposity across childhood.

OBJECTIVE

To investigate the continuity and stability of the home environment from ages 4 to 12, and bi-directional relationships between the home environment and BMI-SDS from ages 4 to 12.

METHODS

Parents from the Gemini cohort completed the Home Environment Interview (HEI), a comprehensive measure of the obesogenic home environment, when their children were aged 4 and 12 (n = 149 families, n = 298 children). The obesogenic home environment was measured using four composite scores capturing the food, activity, media environments, and the overall home environment. Child weights and heights were used to calculate BMI-SDS. Continuity was assessed with Pearson's correlations between scores at each time point, and stability by changes in mean scores over time. Cross-lagged analyses were performed (HEI composites at age 4 to BMI-SDS at age 12 and the reverse) to measure the magnitude and direction of associations.

RESULTS

The home environment showed moderate-to-high continuity from ages 4 to 12 (r = 0.30-0.64). The overall home environment (r = 0.21, p < 0.01) and media composites (r = 0.23, p < 0.01) were cross-sectionally associated with child BMI-SDS at age 12, but not at age 4. Longitudinally, the home media environment at age 4 predicted increases in child BMI-SDS at age 12 (β; 95% CI = 0.18; 0.08,0.28, p < 0.01). No associations were observed for the reverse path, or the remaining composites (the overall, food and activity) in either direction.

CONCLUSION

This study provides evidence that the obesogenic home environment tracks across childhood and highlights the importance of the early home media environment for child weight development. The findings provide insight into key aspects of the home environment that could be targeted when developing obesity treatment or prevention strategies.

The Home Environment Interview and associations with energy balance behaviours and body weight in school-aged children - a feasibility, reliability, and validity study

BACKGROUND

The home environment is thought to influence children's weight trajectories. However, few studies utilise composite measures of the home environment to examine associations with energy balance behaviours and weight. The present study aimed to adapt and update a comprehensive measure of the obesogenic home environment previously developed for pre-schoolers, and explore associations with school-aged children's energy balance behaviours and weight.

METHODS

Families from the Gemini cohort (n = 149) completed the Home Environment Interview (HEI) via telephone when their children were 12 years old. The HEI comprises four composite scores: one for each domain (food, activity and media) of the environment, as well as a score for the overall obesogenic home environment. The primary caregiver also reported each child's height and weight (using standard scales and height charts), diet, physical activity and sedentary screen-based behaviours. A test-retest sample (n = 20) of caregivers completed the HEI a second time, 7-14 days after the initial interview, to establish test-retest reliability.

RESULTS

Children (n = 298) living in 'higher-risk' home environments (a 1 unit increase in the HEI obesogenic risk score) were less likely to consume fruits (OR; 95% CI = 0.40; 0.26-0.61, p < 0.001), and vegetables (0.30; 0.18-0.52, p < 0.001), and more likely to consume energy-dense snack foods (1.71; 1.08-2.69, p = 0.022), convenience foods (2.58; 1.64-4.05, p < 0.001), and fast foods (3.09; 1.90-5.04, p < 0.001). Children living in more obesogenic home environments also engaged in more screen-time (β (SE) = 4.55 (0.78), p < 0.001), spent more time playing video games (β (SE) = 1.56 (0.43), p < 0.001), and were less physically active (OR; 95% CI = 0.57; 0.40-0.80, p < 0.01). Additionally, there was a positive association between higher-risk overall home environment composite score and higher BMI-SDS (β (SE) = 0.23 (0.09), p < 0.01). This finding was mirrored for the home media composite (β (SE) = 0.12 (0.03), p < 0.001). The individual home food and activity composite scores were not associated with BMI-SDS.

CONCLUSION

Findings reveal associations between the overall obesogenic home environment and dietary intake, activity levels and screen-based sedentary behaviours, as well as BMI in 12 year olds. These findings suggest that the home environment, and in particular the home media environment, may be an important target for obesity prevention strategies.

Factorial validation analysis of the Baby and Children's Eating Behavior Questionnaires in Samoa

Survey instruments for assessing eating behaviors in infancy and early childhood have yet to be validated among Pacific Islanders, among whom the prevalence of pediatric obesity is steadily increasing. This study aimed to evaluate Baby Eating Behavior Questionnaire (BEBQ) and Children's Eating Behavior Questionnaire (CEBQ) factor structures against data collected from mother-infant dyads in Samoa. The BEBQ was administered across two time points: approximately 2 months (mean = 2.37 [SD = 0.34]; N = 105) and 4 months postpartum (mean = 4.22 [SD = 0.44]; N = 117). The CEBQ was administered at approximately 21 months postpartum (mean = 21.45 [SD = 1.72]; N = 113). Both the original four-factor BEBQ and seven-factor CEBQ models failed to replicate in confirmatory factor analyses. BEBQ data from 2 and 4 months demonstrated acceptable fit to a nine-item, two factor model, generated by elimination of factors with low internal reliability. A series of exploratory factor analyses on CEBQ data from 21 months postpartum ultimately revealed 16-item, three-factor structure. There was little correlation between BEBQ and CEBQ scores, suggesting either that infant feeding behaviors before and after weaning are not strongly associated, or that the BEBQ and CEBQ function better in cross-sectional, rather than longitudinal analyses. Newly derived CEBQ factors raise concerns regarding whether original CEBQ items and factors were sufficiently theoretically distinct. Study results suggest that demographic and cultural differences may impact both BEBQ and CEBQ factor structure. Further qualitative research is necessary to address these issues.

Baby's first bites: Association between observed maternal feeding behavior and infant vegetable intake and liking

Positive experiences with the introduction of solid food in infancy may lead to positive associations with feeding in both parent and infant. During this transitional period, parental feeding behavior and infant eating behavior might mutually reinforce each other. A feeding style that is found to be associated with positive child eating behavior, is sensitive feeding. In the present study we tested bidirectional prospective relations between mother and infant behavior in a cross-lagged model using observations of two feeds on two consecutive days on which the first bites of solid food were offered. The sample consisted of 246 first-time mothers and their infants, whose feeding interactions were videotaped during two home visits. Maternal sensitive feeding behavior (consisting of responsiveness to child feeding cues, general sensitivity and non-intrusiveness) and maternal positive and negative affect were coded. In addition, infant vegetable intake was weighed and vegetable liking was reported by mother. Results showed at least some stability of maternal feeding behavior and infant vegetable intake and liking from the first to the second feed. In addition, during the second feed maternal sensitive feeding and positive affect were associated with infant vegetable intake (r=.34 and r=.14) and liking (r=.33 and r=.39). These associations were mostly absent during the first feed. Finally, infant vegetable liking during the first feed positively predicted maternal sensitive feeding behavior during the second feed (β=.25), suggesting that the infant's first response might influence maternal behavior. Taken together, mother and infant seem more attuned during the second feed than during the first feed. Future studies might include multiple observations over a longer time period, or micro-coding. Such insights can inform prevention programs focusing on optimizing feeding experiences during the weaning period.

Association of Protein Intake during the Second Year of Life with Weight Gain-Related Outcomes in Childhood: A Systematic Review

There is accumulating evidence that early protein intake is related with weight gain in childhood. However, the evidence is mostly limited to the first year of life, whereas the high-weight-gain-velocity period extends up to about 2 years of age. We aimed to investigate whether protein intake during the second year of life is associated with higher weight gain and obesity risk later in childhood. We conducted a systematic review with searches in both PubMed®/MEDLINE® and the Cochrane Central Register of Controlled Trials. Ten studies that assessed a total of 46,170 children were identified. We found moderate-quality evidence of an association of protein intake during the second year of life with fat mass at 2 years and at 7 years. Effects on other outcomes such as body mass index (BMI), obesity risk, or adiposity rebound onset were inconclusive due to both heterogeneity and low evidence. We conclude that higher protein intakes during the second year of life are likely to increase fatness in childhood, but there is limited evidence regarding the association with other outcomes such as body mass index or change in adiposity rebound onset. Further well-designed and adequately powered clinical trials are needed since this issue has considerable public health relevance.

Common etiological architecture underlying reward responsiveness, externally driven eating behaviors, and BMI in childhood: findings from the Gemini twin cohort

BACKGROUND

Studies have reported that impulsivity predicts childhood BMI and that the association is mediated by eating behaviors. One aspect of impulsivity-potentially crucial in the obesity context-is reward responsiveness, which may predispose to responsiveness to palatable food cues. The behavioral susceptibility theory hypothesizes that genetic susceptibility to obesity operates partly via genetically determined differences in appetite regulation. Reward responsiveness may therefore be one of the neuro-endophenotypes that mediates genetic susceptibility to obesity.

OBJECTIVE

To test whether reward responsiveness, eating behaviors, and child BMI share common genetic architecture.

METHODS

We examined reward responsiveness, eating behaviors, and BMI in 5-year-old children from Gemini, a UK birth cohort of 2402 twin pairs born in 2007. All measures were collected by parent report. Reward responsiveness was derived from the Behavioral Approach System. Compulsion to eat and eating for pleasure was measured with the "food responsiveness" scale of the Child Eating Behavior Questionnaire. Wanting to eat in response to environmental food cues was measured with the "external eating" scale of the Dutch Eating Behavior Questionnaire. Maximum-likelihood structural equation modeling was used to establish underlying common genetic and environmental influences.

RESULTS

There were significant positive phenotypic correlations between all traits except for reward responsiveness and BMI. Genetic factors explained the majority of the association between food responsiveness and external eating (74%, 95% CI: 61, 87), whereas common shared environmental factors explained the majority of the associations between reward responsiveness with both food responsiveness (55%, 95% CI: 20, 90) and external eating (70%, 95% CI: 39, 100).

CONCLUSIONS

Our study demonstrates the importance of common environmental factors in the shared etiology between reward responsiveness and childhood eating behaviors. However, the common etiology underlying both reward responsiveness and BMI is unclear, as there was no phenotypic correlation between reward responsiveness and BMI at this age. Further longitudinal research needs to detangle this complex relationship throughout development.

Variation in the Heritability of Child Body Mass Index by Obesogenic Home Environment

Importance

The early obesogenic home environment is consistently identified as a key influence on child weight trajectories, but little research has examined the mechanisms of that influence. Such research is essential for the effective prevention and treatment of overweight and obesity.

Objective

To test behavioral susceptibility theory's hypothesis that the heritability of body mass index (BMI) is higher among children who live in more obesogenic home environments.

Design, Setting, and Participants

This study was a gene-environment interaction twin study that used cross-sectional data from 925 families (1850 twins) in the Gemini cohort (a population-based prospective cohort of twins born in England and Wales between March and December 2007). Data were analyzed from July to October 2013 and in June 2018.

Exposures

Parents completed the Home Environment Interview, a comprehensive measure of the obesogenic home environment in early childhood. Three standardized composite scores were created to capture food, physical activity, and media-related influences in the home; these were summed to create an overall obesogenic risk score. The 4 composite scores were split on the mean, reflecting higher-risk and lower-risk home environments.

Main Outcomes and Measures

Quantitative genetic model fitting was used to estimate heritability of age-adjusted and sex-adjusted BMI (BMI SD score, estimated using British 1990 growth reference data) for children living in lower-risk and higher-risk home environments.

Results

Among 1850 twins (915 [49.5%] male and 935 [50.5%] female; mean [SD] age, 4.1 [0.4] years), the heritability of BMI SD score was significantly higher among children living in overall higher-risk home environments (86%; 95% CI, 68%-89%) compared with those living in overall lower-risk home environments (39%; 95% CI, 21%-57%). The findings were similar when examining the heritability of BMI in the separate food and physical activity environment domains.

Conclusions and Relevance

These findings support the hypothesis that obesity-related genes are more strongly associated with BMI in more obesogenic home environments. Modifying the early home environment to prevent weight gain may be particularly important for children genetically at risk for obesity.

Sources and pattern of protein intake and risk of overweight or obesity in young UK twins

High protein intake in young children is associated with excess gains in weight and body fat, but the specific role of different protein sources has yet to be described. The study aimed to investigate the role of different types of protein in the post-weaning stage on weight, BMI and overweight/obesity at 60 months. Intakes of animal, dairy and plant protein and a dietary pattern characterising variation in protein types at 21 months of age were estimated using a 3-d diet diary in a cohort of 2154 twins; weight and height were recorded every 3 months from birth to 60 months. Longitudinal mixed-effect models investigated the associations between sources of protein intake or dietary pattern scores and BMI, weight and overweight/obesity from 21 months up to 60 months. Adjusting for confounders, dairy protein intake at 21 months was positively associated with greater weight (46 (95 % CI 21, 71) g and BMI up to 60 months (0·04 (95 % CI 0·004, 0·070) kg/m2) and the odds of overweight/obesity at 3 years (OR 1·12; 95 % CI 1·00, 1·24). Milk showed associations of similar magnitude. A dietary pattern low in dairy protein and high in plant protein was associated with lower weight gain up to 60 months, but not overweight/obesity. Intake of dairy products in early childhood is most strongly associated with weight gain, compared with other protein sources. A dietary pattern characterised by lower protein intake and greater protein source diversity at 2 years may confer a lower risk of excess weight gain.

Genetic and Environmental Influences on Developmental Milestones and Movement: Results From the Gemini Cohort Study

PURPOSE

Variability in the timing of infant developmental milestones is poorly understood. We used a twin analysis to estimate genetic and environmental influences on motor development and activity levels in infancy.

METHOD

Data were from the Gemini Study, a twin birth cohort of 2,402 families with twins born in the United Kingdom in 2007. Parents reported motor activity level for each of the twins at age 3 months using the Revised Infant Behavior Rating Scale and reported the ages at which they first sat unsupported, crawled, and walked unaided.

RESULTS

Activity level at 3 months and ages when first sitting and crawling were about equally influenced by the shared family environment (45%-54%) and genes (45%-48%). Genetic influences dominated for age when children took their first independent steps (84%).

CONCLUSION

Aspects of the shared family environment appear to be important influences on motor activity levels and early milestones, although the timing of walking may have a stronger genetic influence. Further research to identify the specific environmental and genetic factors that promote early activity may be important for longer-term health outcomes.

Emotional over- and under-eating in early childhood are learned not inherited

Emotional overeating (EOE) has been associated with increased obesity risk, while emotional undereating (EUE) may be protective. Interestingly, EOE and EUE tend to correlate positively, but it is unclear whether they reflect different aspects of the same underlying trait, or are distinct behaviours with different aetiologies. Data were from 2054 five-year-old children from the Gemini twin birth cohort, including parental ratings of child EOE and EUE using the Child Eating Behaviour Questionnaire. Genetic and environmental influences on variation and covariation in EUE and EOE were established using a bivariate Twin Model. Variation in both behaviours was largely explained by aspects of the environment completely shared by twin pairs (EOE: C = 90%, 95% CI: 89%-92%; EUE: C = 91%, 95% CI: 90%-92%). Genetic influence was low (EOE: A = 7%, 95% CI: 6%-9%; EUE: A = 7%, 95% CI: 6%-9%). EOE and EUE correlated positively (r = 0.43, p < 0.001), and this association was explained by common shared environmental influences (BivC = 45%, 95% CI: 40%-50%). Many of the shared environmental influences underlying EUE and EOE were the same (r_C = 0.50, 95% CI: 0.44, 0.55). Childhood EOE and EUE are etiologically distinct. The tendency to eat more or less in response to emotion is learned rather than inherited.

Behavioural Susceptibility Theory: Professor Jane Wardle and the Role of Appetite in Genetic Risk of Obesity

PURPOSE OF REVIEW

There is considerable variability in human body weight, despite the ubiquity of the 'obesogenic' environment. Human body weight has a strong genetic basis and it has been hypothesised that genetic susceptibility to the environment explains variation in human body weight, with differences in appetite being implicated as the mediating mechanism; so-called 'behavioural susceptibility theory' (BST), first described by Professor Jane Wardle. This review summarises the evidence for the role of appetite as a mediator of genetic risk of obesity.

RECENT FINDINGS

Variation in appetitive traits is observable from infancy, drives early weight gain and is highly heritable in infancy and childhood. Obesity-related common genetic variants identified through genome-wide association studies show associations with appetitive traits, and appetite mediates part of the observed association between genetic risk and adiposity. Obesity results from an interaction between genetic susceptibility to overeating and exposure to an 'obesogenic' food environment.

Food fussiness and food neophobia share a common etiology in early childhood

BACKGROUND

'Food fussiness' (FF) is the tendency to be highly selective about which foods one is willing to eat, and emerges in early childhood; 'food neophobia' (FN) is a closely related characteristic but specifically refers to rejection of unfamiliar food. These behaviors are associated, but the extent to which their etiological architecture overlaps is unknown. The objective of this study was to quantify the relative contribution of genetic and environmental influences to variation in FF and FN in early childhood; and to establish the extent to which they share common genetic and environmental influences.

METHOD

Participants were 1,921 families with 16-month-old twins from the Gemini birth cohort. Parents completed the Child Eating Behaviour Questionnaire which included three FF items and four FN items. Bivariate quantitative genetic modeling was used to quantify: (a) genetic and environmental contributions to variation in FF and FN; and (b) the extent to which genetic or environmental influences on FF and FN are shared across the traits.

RESULTS

Food fussiness and FN were strongly correlated (r = .72, p < .001). Proportions of variation in FF were equally explained by genetic (.46; 95% CI: 0.41-0.52) and shared environmental influences (.46; 95% CI: 0.41-0.51). Shared environmental effects accounted for a significantly lower proportion of variation in FN (.22; 95% CI: 0.14-0.30), but genetic influences were not significantly different from those on FF (.58, 95% CI: 0.50-0.67). FF and FN largely shared a common etiology, indicated by high genetic (.73; 95% CI: 0.67-0.78) and shared environmental correlations (.78; 95% CI: 0.69-0.86) across the two traits.

CONCLUSIONS

Food fussiness and FN both show considerable heritability at 16 months but shared environmental factors, for example the home environment, influenced more interindividual differences in the expression of FF than in FN. FF and FN largely share a common etiology.

Maternal feeding practices and fussy eating in toddlerhood: a discordant twin analysis

BACKGROUND

Parental feeding practices are thought to play a causal role in shaping a child's fussiness; however, a child-responsive model suggests that feeding practices may develop in response to a child's emerging appetitive characteristics. We used a novel twin study design to test the hypothesis that mothers vary their feeding practices for twin children who differ in their 'food fussiness', in support of a child-responsive model.

METHODS

Participants were mothers and their 16 month old twin children (n = 2026) from Gemini, a British twin birth cohort of children born in 2007. Standardized psychometric measures of maternal 'pressure to eat', 'restriction' and 'instrumental feeding', as well as child 'food fussiness', were completed by mothers. Within-family analyses examined if twin-pair differences in 'food fussiness' were associated with differences in feeding practices using linear regression models. In a subset of twins (n = 247 pairs) who were the most discordant (highest quartile) on 'food fussiness' (difference score ≥ .50), Paired Samples T-test were used to explore the magnitude of differences in feeding practices between twins. Between-family analyses used Complex Samples General Linear Models to examine associations between feeding practices and 'food fussiness'.

RESULTS

Within-pair differences in 'food fussiness' were associated with differential 'pressure to eat' and 'instrumental feeding' (ps < .001), but not with 'restriction'. In the subset of twins most discordant on 'food fussiness', mothers used more pressure (p < .001) and food rewards (p < .05) with the fussier twin. Between-family analyses indicated that 'pressure to eat' and 'instrumental feeding' were positively associated with 'food fussiness', while 'restriction' was negatively associated with 'food fussiness' (ps < .001).

CONCLUSIONS

Mothers appear to subtly adjust their feeding practices according to their perceptions of their toddler's emerging fussy eating behavior. Specifically, the fussier toddler is pressured more than their less fussy co-twin, and is more likely to be offered food rewards. Guiding parents on how to respond to fussy eating may be an important aspect of promoting feeding practices that encourage food acceptance.

Parental Reports of Infant and Child Eating Behaviors are not Affected by Their Beliefs About Their Twins' Zygosity

Parental perception of zygosity might bias heritability estimates derived from parent rated twin data. This is the first study to examine if similarities in parental reports of their young twins’ behavior were biased by beliefs about their zygosity. Data were from Gemini, a British birth cohort of 2402 twins born in 2007. Zygosity was assessed twice, using both DNA and a validated parent report questionnaire at 8 (SD = 2.1) and 29 months (SD = 3.3). 220/731 (8 months) and 119/453 (29 months) monozygotic (MZ) pairs were misclassified as dizygotic (DZ) by parents; whereas only 6/797 (8 months) and 2/445 (29 months) DZ pairs were misclassified as MZ. Intraclass correlations for parent reported eating behaviors (four measured at 8 months; five at 16 months) were of the same magnitude for correctly classified and misclassified MZ pairs, suggesting that parental zygosity perception does not influence reporting on eating behaviors of their young twins.

Meal size is a critical driver of weight gain in early childhood

Larger serving sizes and more frequent eating episodes have been implicated in the rising prevalence of obesity at a population level. This study examines the relative contributions of meal size and frequency to weight gain in a large sample of British children. Using 3-day diet diaries from 1939 children aged 21 months from the Gemini twin cohort, we assessed prospective associations between meal size, meal frequency and weight gain from two to five years. Separate longitudinal analyses demonstrated that every 10 kcal increase in meal size was associated with 1.5 g/wk or 4% (p = 0.005) faster growth rate, while meal frequency was not independently associated with growth (β = 0.3 g/wk p = 0.20). Including both meal parameters in the model strengthened associations (meal size: β = 2.6 g/wk, p < 0.001; meal frequency: β = 1.0 g/wk, p = 0.001). Taken together, the implication is that meal size promotes faster growth regardless of frequency, but meal frequency has a significant effect only if meal size is assumed to be held constant. Clearer advice on meal size and frequency, especially advice on appropriate meal size, may help prevent excess weight gain.

Energy and nutrient intakes of young children in the UK: findings from the Gemini twin cohort

Data on the diets of young children in the UK are limited, despite growing evidence of the importance of early diet for long-term health. We used the largest contemporary dietary data set to describe the intake of 21-month-old children in the UK. Parents of 2336 children aged 21 months from the UK Gemini twin cohort completed 3-d diet diaries in 2008/2009. Family background information was obtained from questionnaires completed 8 months after birth. Mean total daily intakes of energy, macronutrients (g and %E) and micronutrients from food and beverages, including and excluding supplements, were derived. Comparisons with UK dietary reference values (DRV) were made using t tests and general linear regression models, respectively. Daily energy intake (kJ), protein (g) and most micronutrients exceeded DRV, except for vitamin D and Fe, where 96 or 84 % and 70 or 6 % of children did not achieve the reference nutrient intake or lower reference nutrient intake (LRNI), respectively, even with supplementation. These findings reflect similar observations in the smaller sample of children aged 18-36 months in the National Diet and Nutrition Survey. At a population level, young children in the UK are exceeding recommended daily intakes of energy and protein, potentially increasing their risk of obesity. The majority of children are not meeting the LRNI for vitamin D, largely reflecting inadequate use of the supplements recommended at this age. Parents may need more guidance on how to achieve healthy energy and nutrient intakes for young children.

Common genetic architecture underlying young children's food fussiness and liking for vegetables and fruit

BACKGROUND

Food fussiness (FF) is common in early childhood and is often associated with the rejection of nutrient-dense foods such as vegetables and fruit. FF and liking for vegetables and fruit are likely all heritable phenotypes; the genetic influence underlying FF may explain the observed genetic influence on liking for vegetables and fruit. Twin analyses make it possible to get a broad-based estimate of the extent of the shared genetic influence that underlies these traits.

OBJECTIVE

We quantified the extent of the shared genetic influence that underlies FF and liking for vegetables and fruit in early childhood with the use of a twin design.

DESIGN

Data were from the Gemini cohort, which is a population-based sample of twins born in England and Wales in 2007. Parents of 3-y-old twins (n= 1330 pairs) completed questionnaire measures of their children's food preferences (liking for vegetables and fruit) and the FF scale from the Children's Eating Behavior Questionnaire. Multivariate quantitative genetic modeling was used to estimate common genetic influences that underlie FF and liking for vegetables and fruit.

RESULTS

Genetic correlations were significant and moderate to large in size between FF and liking for both vegetables (-0.65) and fruit (-0.43), which indicated that a substantial proportion of the genes that influence FF also influence liking. Common genes that underlie FF and liking for vegetables and fruit largely explained the observed phenotypic correlations between them (68-70%).

CONCLUSIONS

FF and liking for fruit and vegetables in young children share a large proportion of common genetic factors. The genetic influence on FF may determine why fussy children typically reject fruit and vegetables.

Dietary protein intake is associated with body mass index and weight up to 5 y of age in a prospective cohort of twins

BACKGROUND

Few large epidemiologic studies have investigated the role of postweaning protein intake in excess weight and adiposity of young children, despite children in the United Kingdom consistently consuming protein in excess of their physiologic requirements.

OBJECTIVE

We investigated whether a higher proportion of protein intake from energy beyond weaning is associated with greater weight gain, higher body mass index (BMI), and risk of overweight or obesity in children up to 5 y of age.

DESIGN

Participants were 2154 twins from the Gemini cohort. Dietary intake was collected by using a 3-d diet diary when the children had a mean age of 21 mo. Weight and height were collected every 3 mo, from birth to 5 y. Longitudinal models investigated associations of protein intake with BMI, weight, and height, with adjustment for age at diet diary, sex, total energy intake, birth weight/length, and rate of prior growth and clustering within families. Logistic regression investigated protein intake in relation to the odds of overweight or obesity at 3 and 5 y of age.

RESULTS

A total of 2154 children had a mean ± SD of 5.7 ± 3.2 weight and height measurements up to 5 y. Total energy from protein was associated with higher BMI (β = 0.043; 95% CI: 0.011, 0.075) and weight (β = 0.052; 95% CI: 0.031, 0.074) but not height (β = 0.088; 95% CI: -0.038, 0.213) between 21 mo and 5 y. Substituting percentage energy from fat or carbohydrate for percentage energy from protein was associated with decreases in BMI and weight. Protein intake was associated with a trend in increased odds of overweight or obesity at 3 y (OR = 1.10; 95% CI 0.99, 1.22, P = 0.075), but the effect was not statistically significant at 5 y.

CONCLUSION

A higher proportion of energy from protein during the complementary feeding stage is associated with greater increases in weight and BMI in early childhood in this large cohort of United Kingdom children.

Appetitive traits and food intake patterns in early life

BACKGROUND

High food responsiveness (FR) and low satiety responsiveness (SR) are 2 appetitive traits that have been associated longitudinally with risk of excessive weight gain; however, to our knowledge, no studies have examined the associations between these traits and eating patterns in daily life in young children.

OBJECTIVE

We tested the hypothesis that higher FR is independently associated with a higher meal frequency and that lower SR is associated with a larger meal size.

DESIGN

Data were from 1102 families (2203 children) from the Gemini twin birth cohort. Appetite was assessed with the use of the Child Eating Behavior Questionnaire when the children were 16 mo old (mean ± SD: 15.73 ± 1.08 mo old), and meal frequency (eating occasions per day) and meal size (kilojoules per eating occasion) were determined from 3-d diet diaries completed by parents when the children were 21 mo old (mean ± SD: 20.65 ± 1.10 mo old). Complex samples general linear models were used to explore cross-sectional associations between appetitive traits and meal variables.

RESULTS

After adjustment for the covariates gestational age, birth weight, sex, difference in age at diet-diary completion, and appetite measurement, higher FR was associated with more-frequent meals (B ± SE: 0.13 ± 0.04; P = 0.001) but not with meal size (P = 0.41), and lower SR was associated with a larger meal size (B ± SE: -47.61 ± 8.79; P < 0.001) but not with meal frequency (P = 0.15).

CONCLUSIONS

FR and SR predict different eating variables with more food-responsive children eating more frequently, whereas less-satiety-responsive children eat more food on each eating occasion. Different strategies may be required to reduce the potential effects of FR and SR on weight gain.

Sleep and nighttime energy consumption in early childhood: a population-based cohort study

BACKGROUND

Shorter sleep is a risk factor for weight gain in young children. Experimental studies show that sleep deprivation is associated with higher nighttime energy intake, but no studies have examined the patterning of energy intake in relation to nighttime sleep duration in young children.

OBJECTIVES

The objectives of the study were to test the hypothesis that shorter-sleeping children would show higher nighttime energy intake and to examine whether the additional calories were from drinks, snacks or meals.

METHODS

Participants were 1278 families from the Gemini twin cohort, using data from one child per family selected at random to avoid clustering effects. Nighttime sleep duration was measured at 16 months of age using the Brief Infant Sleep Questionnaire. Energy intake by time of day and eating episode (meal, snack, drink) were derived from 3-day diet diaries completed when children were 21 months.

RESULTS

Consistent with our hypothesis, shorter-sleeping children consumed more calories at night only (linear trend P < 0.001), with those sleeping <10 h consuming on average 120 calories (15.2% of daily intake) more at night than those sleeping ≥13 h. The majority of nighttime intake was from milk drinks. Associations remained after adjusting for age, sex, birth weight, gestational age, maternal education, weight and daytime sleep.

CONCLUSIONS

Shorter-sleeping, young children consume more calories, predominantly at night, and from milk drinks. Parents should be aware that providing milk drinks at night may contribute to excess intake. This provides a clear target for intervention that may help address associations between sleep and weight observed in later childhood.

The relationship between appetite and food preferences in British and Australian children

Background

Appetitive traits and food preferences are key determinants of children’s eating patterns but it is unclear how these behaviours relate to one another. This study explores relationships between appetitive traits and preferences for fruits and vegetables, and energy dense, nutrient poor (noncore) foods in two distinct samples of Australian and British preschool children.

Methods

This study reports secondary analyses of data from families participating in the British GEMINI cohort study (n = 1044) and the control arm of the Australian NOURISH RCT (n = 167). Food preferences were assessed by parent-completed questionnaire when children were aged 3–4 years and grouped into three categories; vegetables, fruits and noncore foods. Appetitive traits; enjoyment of food, food responsiveness, satiety responsiveness, slowness in eating, and food fussiness were measured using the Children’s Eating Behaviour Questionnaire when children were 16 months (GEMINI) or 3–4 years (NOURISH). Relationships between appetitive traits and food preferences were explored using adjusted linear regression analyses that controlled for demographic and anthropometric covariates.

Results

Vegetable liking was positively associated with enjoyment of food (GEMINI; β = 0.20 ± 0.03, p < 0.001, NOURISH; β = 0.43 ± 0.07, p < 0.001) and negatively related to satiety responsiveness (GEMINI; β = -0.19 ± 0.03, p < 0.001, NOURISH; β = -0.34 ± 0.08, p < 0.001), slowness in eating (GEMINI; β = -0.10 ± 0.03, p = 0.002, NOURISH; β = -0.30 ± 0.08, p < 0.001) and food fussiness (GEMINI; β = −0.30 ± 0.03, p < 0.001, NOURISH; β = -0.60 ± 0.06, p < 0.001). Fruit liking was positively associated with enjoyment of food (GEMINI; β = 0.18 ± 0.03, p < 0.001, NOURISH; β = 0.36 ± 0.08, p < 0.001), and negatively associated with satiety responsiveness (GEMINI; β = −0.13 ± 0.03, p < 0.001, NOURISH; β = −0.24 ± 0.08, p = 0.003), food fussiness (GEMINI; β = -0.26 ± 0.03, p < 0.001, NOURISH; β = −0.51 ± 0.07, p < 0.001) and slowness in eating (GEMINI only; β = -0.09 ± 0.03, p = 0.005). Food responsiveness was unrelated to liking for fruits or vegetables in either sample but was positively associated with noncore food preference (GEMINI; β = 0.10 ± 0.03, p = 0.001, NOURISH; β = 0.21 ± 0.08, p = 0.010).

Conclusion

Appetitive traits linked with lower obesity risk were related to lower liking for fruits and vegetables, while food responsiveness, a trait linked with greater risk of overweight, was uniquely associated with higher liking for noncore foods.

Electronic supplementary material

The online version of this article (doi:10.1186/s12966-015-0275-4) contains supplementary material, which is available to authorized users.

The Obesogenic Quality of the Home Environment: Associations with Diet, Physical Activity, TV Viewing, and BMI in Preschool Children

Objectives

The home environment is thought to play a key role in early weight trajectories, although direct evidence is limited. There is general agreement that multiple factors exert small individual effects on weight-related outcomes, so use of composite measures could demonstrate stronger effects. This study therefore examined whether composite measures reflecting the ‘obesogenic’ home environment are associated with diet, physical activity, TV viewing, and BMI in preschool children.

Methods

Families from the Gemini cohort (n = 1096) completed a telephone interview (Home Environment Interview; HEI) when their children were 4 years old. Diet, physical activity, and TV viewing were reported at interview. Child height and weight measurements were taken by the parents (using standard scales and height charts) and reported at interview. Responses to the HEI were standardized and summed to create four composite scores representing the food (sum of 21 variables), activity (sum of 6 variables), media (sum of 5 variables), and overall (food composite/21 + activity composite/6 + media composite/5) home environments. These were categorized into ‘obesogenic risk’ tertiles.

Results

Children in ‘higher-risk’ food environments consumed less fruit (OR; 95% CI = 0.39; 0.27–0.57) and vegetables (0.47; 0.34–0.64), and more energy-dense snacks (3.48; 2.16–5.62) and sweetened drinks (3.49; 2.10–5.81) than children in ‘lower-risk’ food environments. Children in ‘higher-risk’ activity environments were less physically active (0.43; 0.32–0.59) than children in ‘lower-risk’ activity environments. Children in ‘higher-risk’ media environments watched more TV (3.51; 2.48–4.96) than children in ‘lower-risk’ media environments. Neither the individual nor the overall composite measures were associated with BMI.

Conclusions

Composite measures of the obesogenic home environment were associated as expected with diet, physical activity, and TV viewing. Associations with BMI were not apparent at this age.

The role of infant appetite in extended formula feeding

OBJECTIVE

Parental decision-making around extended formula feeding (12 months+) has not been explored previously. This study tested the hypotheses that extended formula milk use (i) is associated with poorer appetite and (ii) supplements lower food intake.

METHODS

Appetite was assessed with the Child Eating Behaviour Questionnaire (CEBQ) in 3854 twin children aged 16 months. Diet was assessed from 3-day diaries in 2714 children at 21 months. Parents reported their children's weight at 24 months. Associations between formula feeding and (1) appetite, (2) energy intake and (3) weight were examined. 35 mothers were interviewed when the children were 7 years old to explore retrospectively their reasons for extended formula feeding.

RESULTS

Formula consumers (13% of the sample) scored significantly differently than non-formula consumers on five of the six CEBQ subscales, indicating lower appetite avidity: 'food responsiveness' (2.02 vs 2.22, respectively),'enjoyment of food' (3.99 vs 4.20), 'satiety responsiveness' (2.89 vs 2.65), 'slowness in eating' (2.63 vs 2.46) and 'food fussiness' (2.34 vs 2.14). Formula consumers had a significantly lower percentage of daily energy intake from food (70% vs 74%); however, total daily energy intake did not differ significantly from non-consumers (4315 vs 4373 kJ). At interview, mothers reported supplementing their child's diet with formula because of 'picky eating' and concerns about inadequate food intake.

CONCLUSIONS

High formula milk intake is associated with picky-eating behaviours, but seems to act as a substitute for rather than a supplement to solid food. Prospective and intervention studies are needed to determine whether extended formula feeding has an enduring impact on weight trajectories, eating behaviours or health.

Nighttime sleep duration and hedonic eating in childhood

Background:

Higher food intake is implicated in the elevated risk of obesity associated with shorter sleep in children, but the mechanisms driving higher intake are uncertain. Research in adults suggests that acute sleep deprivation affects brain reward systems, which increases responsiveness to palatable foods. However, there have been few studies addressing habitual sleep duration, and few in children, among whom the strongest associations with body mass index (BMI) are seen.

Objective:

The objective of this study is to test the hypothesis that shorter-sleeping children are more food responsive and explore the mediation of the relationship between sleep and weight by food responsiveness (FR).

Methods:

Participants were families from Gemini, a UK twin birth cohort, who had provided complete information on their children's sleep and appetite at age 5 years (n=1008). One child from each twin pair was randomly selected for analyses. Nighttime sleep duration was calculated from parent-reported bedtime and wake time, and categorised as shorter, adequate or longer according to age-specific reference values. FR was assessed with the Child Eating Behaviour Questionnaire. BMI s.d. scores (BMI-SDS) were calculated from parent-measured heights and weights using the UK 1990 reference data and were available for 494 children.

Results:

There was a significant linear association between shorter sleep and higher FR at age 5 years (P for linear trend=0.032), which was maintained after adjusting for age, sex, birth weight, maternal education and BMI-SDS. In the subset with BMI data at age 5 years, shorter sleep was associated with higher BMI-SDS (P=0.026) as expected. Testing for mediation by adding FR to the model attenuated the linear relationship to borderline significance (P=0.049), suggesting partial mediation.

Conclusions:

Shorter sleep in childhood is associated with higher FR, which may partly explain the association between shorter sleep and adiposity in childhood.

The CODATwins Project: The Cohort Description of Collaborative Project of Development of Anthropometrical Measures in Twins to Study Macro-Environmental Variation in Genetic and Environmental Effects on Anthropometric Traits

For over 100 years, the genetics of human anthropometric traits has attracted scientific interest. In particular, height and body mass index (BMI, calculated as kg/m2) have been under intensive genetic research. However, it is still largely unknown whether and how heritability estimates vary between human populations. Opportunities to address this question have increased recently because of the establishment of many new twin cohorts and the increasing accumulation of data in established twin cohorts. We started a new research project to analyze systematically (1) the variation of heritability estimates of height, BMI and their trajectories over the life course between birth cohorts, ethnicities and countries, and (2) to study the effects of birth-related factors, education and smoking on these anthropometric traits and whether these effects vary between twin cohorts. We identified 67 twin projects, including both monozygotic (MZ) and dizygotic (DZ) twins, using various sources. We asked for individual level data on height and weight including repeated measurements, birth related traits, background variables, education and smoking. By the end of 2014, 48 projects participated. Together, we have 893,458 height and weight measures (52% females) from 434,723 twin individuals, including 201,192 complete twin pairs (40% monozygotic, 40% same-sex dizygotic and 20% opposite-sex dizygotic) representing 22 countries. This project demonstrates that large-scale international twin studies are feasible and can promote the use of existing data for novel research purposes.

Parental control over feeding in infancy. Influence of infant weight, appetite and feeding method

•

Mothers vary in the control they exert over milk feeding in infancy.

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Control is associated with both feeding method and infant characteristics.

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Mothers are more likely to pressure infants who are lighter or have smaller appetites.

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Mothers are more likely to restrict bottle-fed infants who have a larger appetite.

Background and objective: Parental control over feeding has been linked to child overweight. Parental control behaviours have been assumed to be exogenous to the child, but emerging evidence suggests they are also child-responsive. This study tests the hypothesis that parental control in early infancy is responsive to infant appetite and weight. Subjects and methods: Participants were 1920 mothers from the Gemini twin cohort, using one randomly selected child per family. Data come from questionnaires completed when the children were approximately 8 months. Mothers completed measures of ‘pressure’ and ‘restriction’, reported feeding method (breast- and bottle feeding), rated their infant's appetite during the first 3 months, provided health professional recorded weight measurements, and reported their concerns about their infant's weight. Logistic regression examined predictors of ‘pressure’ and ‘restriction’, adjusting for maternal demographics and BMI. Interactions between feeding method and control were also tested. Results: ‘Pressure’ was associated with lower birth weight (OR = 0.79, 95% CI: 0.65–0.97), greater concern about underweight (OR = 1.88, 1.29–2.75), and lower infant appetite (OR = 0.59, 0.47–0.75). ‘Restriction’ was associated with higher appetite (OR = 1.44, 1.09–1.89) and bottle feeding (OR = 2.86, 2.18–3.75). A significant interaction with feeding method indicated that infants with high appetites were more likely to be restricted only if they were bottle-fed (OR = 1.52, 1.13–2.04). Conclusion: Mothers vary in their levels of control over milk-feeding and this is partly responsive to the infant's characteristics. They tend to pressure infants who are lighter and have a smaller appetite, and restrict infants with larger appetites if they are bottle-fed. Guidance on infant feeding may be better received if it acknowledges that parents respond to infant characteristics in order to achieve their feeding goals.

Primary caregiver knowledge of paediatric physical activity recommendations in the United Kingdom and its association with caregiver behaviour: an observational study

Background

Most children in affluent developed countries do not meet basic physical activity recommendations. This study assessed primary caregiver knowledge of the UK recommendations on physical activity for children and examined the relationship between knowledge and components of parental support and modelling of physical activity.

Methods

Data were from a large, community-based twin birth cohort. Primary caregivers were invited to take part in a telephone interview on the home food and activity environment that included a question on knowledge of the minimum amount of physical activity recommended in UK child guidelines. Socio-demographic variables (maternal age, BMI, education, ethnicity and presence of co-habiting partner) were available from previously completed questionnaires. Parental support and modelling of physical activity variables were assessed during the telephone interview. Binary logistic regression analyses examined the relationship between knowledge and socio-demographic variables and components of parental support and modelling of physical activity.

Results

1,113 families took part in the interview. Only 21% of participants knew the recommended amount of physical activity for children. Higher maternal education was associated with knowledge of the recommendation (Odds Ratio (OR) 2.82; 95% Confidence Interval (CI) 1.66, 4.79, p < 0.001). Knowledge of the recommendation was associated with communicating positive messages about physical activity to child (OR 1.52; 95% CI 1.12, 2.06, p = 0.008), watching the child participating in physical activity (OR 1.69; 95% CI 1.11, 2.55,p = 0.013) and showing the child they enjoyed physical activity themselves (OR 1.51; 95% CI 1.08, 2.12,p = 0.016) but not associated with encouraging the child to be active, doing physical activity with the child, being active in front of the child or showing enthusiasm about being active.

Conclusions

Most primary caregivers in the UK do not know how much physical activity is recommended for children but those who do may be more supportive of physical activity for their child. Wider dissemination of the guidelines could be an important step in increasing population levels of physical activity.

Associations between infant feeding and the size, tempo and velocity of infant weight gain: SITAR analysis of the Gemini twin birth cohort

Objective:

Infant growth trajectories, in terms of size, tempo and velocity, may programme lifelong obesity risk. Timing of breastfeeding cessation and weaning are both implicated in rapid infant growth; we examined the association of both simultaneously with a range of growth parameters.

Design:

Longitudinal population-based twin birth cohort.

Subjects:

The Gemini cohort provided data on 4680 UK infants with a median of 10 (interquartile range=8–15) weight measurements between birth and a median of 6.5 months. Age at breastfeeding cessation and weaning were reported by parents at mean age 8.2 months (s.d.=2.2, range=4–20). Growth trajectories were modelled using SuperImposition by Translation And Rotation (SITAR) to generate three descriptors of individual growth relative to the average trajectory: size (grams), tempo (weeks, indicating the timing of the peak growth rate) and velocity (% difference from average, reflecting mean growth rate). Complex-samples general linear models adjusting for family clustering and confounders examined associations between infant feeding and SITAR parameters.

Results:

Longer breastfeeding (>4 months vs never) was independently associated with lower growth velocity by 6.8% (s.e.=1.3%) and delayed growth tempo by 1.0 (s.e.=0.2 weeks), but not with smaller size. Later weaning (⩾6 months vs <4 months) was independently associated with lower growth velocity by 4.9% (s.e.=1.1%) and smaller size by 102 g (s.e.=25 g).

Conclusions:

Infants breastfed for longer grew slower for longer after birth (later peak growth rate) but were no different in size, while infants weaned later grew slower overall and were smaller but the timing of peak growth did not differ. Slower trajectories with a delayed peak in growth may have beneficial implications for programming later obesity risk. Replication in cohorts with longer follow-up, alternative confounding structures or randomised controlled trials are required to confirm the long-term effects and directionality, and to rule out residual confounding.

Nature and nurture in children's food preferences

BACKGROUND

Health professionals identify food provision in the home as a key influence on children's food preferences. In contrast, parents often perceive children's food preferences to be inborn. One explanation for this discrepancy could be that environmental and genetic influences vary by food type.

OBJECTIVE

We assessed genetic and environmental contributions to preferences for a wide variety of foods in a large pediatric twin sample.

DESIGN

Data were from Gemini, which is a cohort of UK twins born in 2007. Preferences for 114 foods were assessed by parent-completed questionnaire when children were aged 3 y (n = 2686). Foods tried by >75% of respondents were grouped into protein, vegetables, fruit, dairy, starches, and snacks. Quantitative model-fitting analyses were used to assess genetic and environmental influences for each food group.

RESULTS

The genetic influence was higher for vegetables (54%; 95% CI: 47%, 63%), fruit (53%; 95% CI: 45%, 61%), and protein (48%; 95% CI: 40%, 57%) but lower for starches (32%; 95% CI: 26%, 38%), snacks (29%; 95% CI: 24%, 35%), and dairy (27%; 95% CI: 20%, 35%). In contrast, shared-environment effects were higher for snacks (60%; 95% CI: 54%, 65%), starches (57%; 95% CI: 51%, 62%), and dairy (54%; 95% CI: 47%, 60%) and lower for vegetables (35%; 95% CI: 27%, 42%), fruit (35%; 95% CI: 26%, 43%), and protein (37%; 95% CI: 27%, 45%). Nonshared environment effects were small for all foods (11-19%).

CONCLUSIONS

Both genetic and environmental effects were significant for all food groups, but genetic effects dominated for more nutrient-dense foods (vegetables, fruit, and protein), whereas shared environmental effects dominated for snacks, dairy, and starches. These findings endorse the view of health professionals that the home environment is the main determinant of children's liking for energy-dense foods implicated in excessive weight gain but suggest that parents are also correct by identifying innate differences in liking, particularly for nutrient-dense foods that parents and health educators try to encourage.

Sleep and energy intake in early childhood

Background And Objectives:

Shorter sleep is associated with higher weight in children, but little is known about the mechanisms. The aim of this study was to test the hypothesis that shorter sleep was associated with higher energy intake in early childhood.

Methods:

Participants were 1303 families from the Gemini twin birth cohort. Sleep duration was measured using the Brief Infant Sleep Questionnaire when the children were 16 months old. Total energy intake (kcal per day) and grams per day of fat, carbohydrate and protein were derived from 3-day diet diaries completed by parents when children were 21 months old.

Results:

Shorter nighttime sleep was associated with higher total energy intake (P for linear trend=0.005). Children sleeping <10 h consumed around 50 kcal per day more than those sleeping 11–<12 h a night (the optimal sleep duration for children of this age). Differences in energy intake were maintained after adjustment for confounders. As a percentage of total energy intake, there were no significant differences in macronutrient intake by sleep duration. The association between sleep and weight was not significant at this age (P=0.13).

Conclusions:

This study provides the first evidence that shorter nighttime sleep duration has a linear association with higher energy intake early in life. That the effect is observed before emergence of associations between sleep and weight indicates that differences in energy intake may be a mechanism through which sleep influences weight gain.

Predictors of shorter sleep in early childhood

Objective

The aim of this study was to identify socio-demographic and home environmental predictors of shorter sleep in early childhood, and to examine whether effects were mediated by the timing of bedtime or wake time.

Methods

Participants were from Gemini, a British birth cohort of twins, and included 1702 children; one randomly selected from each twin pair. Parents reported night-time sleep duration at an average age of 15.8 months (range 14–27 months) using a modified version of the Brief Infant Sleep Questionnaire. Multiple logistic regression models were used to identify predictors of shorter sleep for this study.

Results

Using a cut-off of <11 h a night, shorter sleep was reported in 14.1% of children. Lower maternal education, non-white ethnic background, being male, low birth weight, living in a home with >1 older child and watching >1 h of TV in the evening were independently associated with shorter sleep. Mediation analyses showed that associations between education, ethnicity, evening TV viewing and sleep were driven predominantly by later bedtimes, while sex differences were driven predominantly by earlier wake times in boys.

Conclusion

In this sample, multiple environmental factors were associated with shorter sleep in young children, with several operating predominantly through later bedtime. An emphasis on the importance of an early and consistent bedtime could help promote healthy sleep and reduce inequalities in child health.

Dietary intake of young twins: nature or nurture?

BACKGROUND

The early years in life are increasingly recognized as a critical period for the development of diet-related behavioral traits. However, discussions continue on the relative role of genes and the environment in determining dietary intake, particularly in young children for whom detailed dietary information is limited.

OBJECTIVES

This study tested the hypothesis that diet in early childhood is primarily determined by the environment rather than by genes. A secondary aim was to characterize the early childhood diet.

DESIGN

A classic twin design used 3-d dietary data collected at age 21 mo from the Gemini cohort. From the full sample of 2402 families with twins, dietary diaries were available for 1216 twin pairs (384 monozygotic and 832 dizygotic pairs) after exclusions. Intakes of macronutrients, food, and beverages were estimated. Twin analyses quantified the contributions of genetic and environmental factors to population variation in intake.

RESULTS

At age 21 mo, children consumed small portions of a wide range of family foods. The shared environment was the predominant determinant, contributing between 66% (95% CI: 52%, 77%; milk-based desserts) and 97% (95% CI: 95%, 98%; juice) of the variation in intake. Genetic factors were estimated to account for between 4% (95% CI: 0%, 10%; savory snacks) and 18% (95% CI: 14%, 23%; bread) of dietary intake variation.

CONCLUSION

Shared environmental influences are the predominant drivers of dietary intake in very young children, indicating the importance of factors such as the home food environment and parental behaviors.

Parent-administered exposure to increase children's vegetable acceptance: a randomized controlled trial

Background

Repeated taste exposure, in combination with small rewards, has been shown to increase children's acceptance of disliked foods. However, previous studies have used direct contact with researchers or professionals for the implementation of the repeated exposure procedure. If mailed taste exposure instructions to parents produced comparable outcomes, this could be a cost-effective and easily disseminable strategy to promote healthier diets in children.

Objective

Our randomized controlled study aimed to test the efficacy and acceptability of mailed materials giving instructions on taste exposure as a means of increasing acceptance of vegetables in preschool-aged children.

Design

Participants were families of 3-year-old twins from the Gemini cohort who took part between March 2011 and April 2012. Families were randomized to a mailed intervention or a no treatment control condition. The intervention involved offering each child 14 daily tastes of a disliked (target) vegetable with a small reward (a sticker) if the child complied.

Main outcome measures

Outcomes were the child's intake of the target vegetable (number of pieces) and parent reports of the child's liking at two baseline (T1 and T2) and one postintervention (T3) behavior assessment.

Results

Record sheets with intake and liking data from T1, T2, and T3 were returned for 472 children, of which 442 were complete (94%). Over the intervention period (T2 to T3) intake and liking of the target vegetable increased significantly more in the intervention group than in the control group (intake: odds ratio 12.05, 95% CI 8.05 to 18.03, P<0.001; liking: odds ratio 12.34, CI 7.97 to 19.12, P<0.001). Acceptability of the procedure was very high among parents who completed the protocol.

Conclusions

Mailed instructions for taste exposure were effective in increasing children's acceptance of an initially disliked vegetable. These results support the value of parent-administered exposure to increase children's vegetable acceptance, and suggest that it can be carried out without direct health professional contact.

Genetics of food intake self-regulation in childhood: literature review and research opportunities

Pediatric obesity results from a daily energy imbalance between intake and expenditure, an imbalance potentially as slight as ~30-50 kcal/day (e.g., a few extra sips of cola or bites of a cookie). That an 'energy gap' so small may be so powerful suggests the importance of understanding mechanisms of food intake self-regulation (FISR). This review focuses on 4 behavioral indices of FISR in childhood: (1) eating in the absence of hunger; (2) eating rate; (3) caloric compensation and satiety responsiveness, and (4) food responsiveness. Evidence from pediatric samples around the world indicates that these traits are associated with body mass index, are heritable, and are linked to polymorphisms in the FTO gene. We review these data, also discussing their relevance to practical issues of parental feeding styles, portion sizes, and health literacy and numeracy. Research gaps and opportunities for future investigation are discussed. Multidisciplinary approaches and study designs that can address gene-environment interactions are needed to advance the science of FISR and stimulate new avenues for childhood obesity prevention.

Family and infant characteristics associated with timing of core and non-core food introduction in early childhood

Objective

To identify family and infant characteristics associated with timing of introduction of two food types: core foods (nutrient-dense) and non-core foods (nutrient-poor) in a population-based sample of mothers and infants.

Method

Participants were 1861 mothers and infants from the Gemini twin birth cohort (one child per family). Family and infant characteristics were assessed when the infants were around 8 months old. Timing of introducing core and non-core foods was assessed at 8 and 15 months. As the distributions of timing were skewed, three similar-sized groups were created for each food type: earlier (core: 1–4 months; non-core: 3–8 months), average (core: 5 months; non-core: 9–10 months), and later introduction (core: 6–12 months; non-core: 11–18 months). Ordinal logistic regression was used to examine predictors of core and non-core food introduction, with bootstrapping to test for differences between the core and non-core models.

Results

Younger maternal age, lower education level, and higher maternal BMI were associated with earlier core and non-core food introduction. Not breastfeeding for at least 3 months and higher birth weight were specifically associated with earlier introduction of core foods. Having older children was specifically associated with earlier introduction of non-core foods.

Conclusion

There are similarities and differences in the characteristics associated with earlier introduction of core and non-core foods. Successful interventions may require a combination of approaches to target both food types.

Genetic and environmental influences on infant sleep

BACKGROUND

Sleep duration is attracting increasing attention in relation to chronic disease risk, but few large-scale studies have investigated the determinants of sleep characteristics in early life. In this study we used data from a large, population-based twin study to examine genetic and environmental influences on sleep duration and sleep difficulties in infancy.

METHODS

Participants were 1931 pairs of young twins (3862 children) from the Gemini twin birth cohort. Sleep patterns were assessed at 15 months by using a modification of the Brief Infant Sleep Questionnaire completed by parents. Outcomes included nighttime and daytime sleep duration and frequency of night waking.

RESULTS

Twin analyses showed that nighttime sleep duration was predominantly influenced by the shared environment (66%, confidence interval [CI] 63%-70%) with a modest genetic effect (26%, CI 22%-30%). A similar pattern was observed for daytime nap duration (shared environment: 57%, CI 53%-62%; genetic effect: 37%, CI 33%-41%) and sleep disturbance (shared environment: 55%, 44%-64%) with a genetic effect of 40% (30%-51%). These estimates were similar for boys and girls.

CONCLUSIONS

These results indicate an important contribution of the shared family environment as well as genes to children's sleep behavior. There is a need for research to identify specific environmental determinants that could provide targets for interventions to improve sleep quality.

Inherited behavioral susceptibility to adiposity in infancy: a multivariate genetic analysis of appetite and weight in the Gemini birth cohort

BACKGROUND

The behavioral susceptibility model proposes that inherited differences in traits such as appetite confer differential risk of weight gain and contribute to the heritability of weight. Evidence that the FTO gene may influence weight partly through its effects on appetite supports this model, but testing the behavioral pathways for multiple genes with very small effects is not feasible. Twin analyses make it possible to get a broad-based estimate of the extent of shared genetic influence between appetite and weight.

OBJECTIVE

The objective was to use multivariate twin analyses to test the hypothesis that associations between appetite and weight are underpinned by shared genetic effects.

DESIGN

Data were from Gemini, a population-based birth cohort of twins (n = 4804) born in 2007. Infant weights at 3 mo were taken from the records of health professionals. Appetite was assessed at 3 mo for the milk-feeding period by using the Baby Eating Behaviour Questionnaire (BEBQ), a parent-reported measure of appetite [enjoyment of food, food responsiveness, slowness in eating (SE), satiety responsiveness (SR), and appetite size (AS)]. Multivariate quantitative genetic modeling was used to test for shared genetic influences.

RESULTS

Significant correlations were found between all BEBQ traits and weight. Significant shared genetic influence was identified for weight with SE, SR, and AS; genetic correlations were between 0.22 and 0.37. Shared genetic effects explained 41-45% of these phenotypic associations.

CONCLUSION

Differences in weight in infancy may be due partly to genetically determined differences in appetitive traits that confer differential susceptibility to obesogenic environments.