Step-Gap in Upward Support: The Role of Biological Relatedness and Childhood Co-residence Duration

OBJECTIVES

Although prior research has detected a step-gap in intergenerational relationships in various aspects, there is a lack of studies examining adult children's support toward their biological parents and stepparents. We investigated (i) whether adult children provide more support to their biological parents than stepparents and (ii) whether the childhood co-residence duration is associated with the support given to stepparents.

METHODS

The data were drawn from the German Family Panel (pairfam). Upward support was indicated by using 3 different measures, namely, financial, practical, and emotional support provided by adult children to their biological parents and stepparents. A path analysis was conducted to detect the potential differences regarding upward support.

RESULTS

More support was channeled toward the biological parents than the stepparents. Moreover, the length of co-residence during childhood and adolescence was positively associated with the frequency of support provided toward the stepparents. Consequently, an increased childhood co-residence duration decreased the step-gap in upward support, although it did not fully eliminate it.

DISCUSSION

The findings showed that stepparents are in a more disadvantaged position than the biological parents regarding receiving support from their adult children. In the context of a high old-age dependency ratio, it is important to recognize that stepparents may not have the opportunity to receive adequate support from their families as compared to individuals with biological children.

Investment by maternal grandmother buffers children against the impacts of adverse early life experiences

Exogenous shocks during sensitive periods of development can have long-lasting effects on adult phenotypes including behavior, survival and reproduction. Cooperative breeding, such as grandparental care in humans and some other mammal species, is believed to have evolved partly in order to cope with challenging environments. Nevertheless, studies addressing whether grandparental investment can buffer the development of grandchildren from multiple adversities early in life are few and have provided mixed results, perhaps owing to difficulties drawing causal inferences from non-experimental data. Using population-based data of English and Welsh adolescents (sample size ranging from 817 to 1197), we examined whether grandparental investment reduces emotional and behavioral problems in children resulting from facing multiple adverse early life experiences (AELEs), by employing instrumental variable regression in a Bayesian structural equation modeling framework to better justify causal interpretations of the results. When children had faced multiple AELEs, the investment of maternal grandmothers reduced, but could not fully erase, their emotional and behavioral problems. No such result was observed in the case of the investment of other grandparent types. These findings indicate that in adverse environmental conditions the investment of maternal grandmothers can improve child wellbeing.

Maternal psychiatric and somatic illness, and the risk of unintentional injuries in children: variation by type of maternal illness, type of injury and child age

BACKGROUND

Maternal mental illness appears to increase the risk of unintentional childhood injuries, which are a common cause of morbidity and mortality in early childhood. However, little is known about the variations in this association by type of injury and child's age, and studies on the effects of maternal somatic illness on children's injury risk are scarce.

METHODS

We used Finnish total population register data from 2000 to 2017 to link 1 369 325 children to their biological mothers and followed them for maternal illness and childhood injuries until the children's sixth birthday. Cox regression models were used to examine the associations between maternal illness and children's injuries by type of illness (neurological, psychiatric and cancer), type of injury (transport injuries, falls, burns, drowning or suffocations, poisonings, exposure to inanimate and animate mechanical forces) and child's age (<1 year-olds, 1-2 year-olds, 3-5 year-olds).

RESULTS

After adjustment for family structure, maternal age at birth, maternal education, income, child's gender, native language and region of residence, children of unwell mothers showed a higher risk of injuries (HR: 1.21, 95% CI: 1.19 to 1.23). This association was clear for maternal neurological (HR: 1.31, 95% CI: 1.26 to 1.36) and psychiatric illnesses (HR: 1.20, 95% CI: 1.18 to 1.23) but inconsistent for cancer. Maternal illness predicted an increased risk of injury across all age groups.

CONCLUSIONS

Maternal mental and somatic illness may both increase children's injury risk. Adequate social and parenting support for families with maternal illness may reduce childhood injury.

Parental Investment by Birth Fathers and Stepfathers : Roles of Mating Effort and Childhood Co-residence Duration

This study investigates the determinants of paternal investment by birth fathers and stepfathers. Inclusive fitness theory predicts higher parental investment in birth children than stepchildren, and this has consistently been found in previous studies. Here we investigate whether paternal investment varies with childhood co-residence duration and differs between stepfathers and divorced birth fathers by comparing the investment of (1) stepfathers, (2) birth fathers who are separated from the child's mother, and (3) birth fathers who still are in a relationship with her. Path analysis was conducted using cross-sectional data from adolescents and younger adults (aged 17-19, 27-29, and 37-39 years) from the German Family Panel (pairfam), collected in 2010-2011 (n = 8326). As proxies of paternal investment, we used financial and practical help, emotional support, intimacy, and emotional closeness, as reported by the children. We found that birth fathers who were still in a relationship with the mother invested the most, and stepfathers invested the least. Furthermore, the investment of both separated fathers and stepfathers increased with the duration of co-residence with the child. However, in the case of financial help and intimacy, the effect of childhood co-residence duration was stronger in stepfathers than in separated fathers. Our findings support inclusive fitness theory and mating effort theory in explaining social behavior and family dynamics in this population. Furthermore, social environment, such as childhood co-residence was associated with paternal investment.

Differential grandparental investment when maternal grandmothers are living versus deceased

Grandparents can increase their inclusive fitness by investing time and resources in their grandchildren. However, not all grandparents make such investments equally, and between-grandparent differences in this regard can be predicted based on paternity uncertainty, lineage and grandparents' sex. Using population-based data for English and Welsh adolescents (n = 1430), we examined whether the death of the most important grandparent (in terms of investment), the maternal grandmother (MGM), changes relative support for existing hypotheses predicting differential grandparental-investment patterns. To contrast the predictions of the grandparental investment hypotheses, we used generalized order-restricted information criterion approximation. We consequently found that, when MGMs are alive, the most-supported hypothesis is 'discriminative grandparental solicitude', which ranks grandparental investment as MGMs > maternal grandfathers (MGFs) > paternal grandmothers (PGMs) > paternal grandfathers (PGFs). However, when MGMs are deceased, the paternity uncertainty hypothesis (MGFs = PGMs > PGFs) receives the most support; this is due to increased investment by PGMs. Thus, when the heaviest investors (i.e. MGMs) are deceased, PGM investments are closer to-but do not exceed-MGF investments.

Grandparental co-residence and grandchild survival: the role of resource competition in a pre-industrial population

Although grandparents are and have been important alloparents to their grandchildren, they are not necessarily only beneficial but can also compete with grandchildren over limited resources. Competition over parental care or other resources may exist especially if grandparents live in the same household with grandchildren and it can be dependent on grandchild age. By utilizing demographic data collected from historic population registers in Finland between 1761 and 1895 (study sample n = 4041) we investigate whether grandparents living in the same household with grandchildren are detrimental or beneficial for grandchild survival. Having a living but not co-residing grandmother or grandfather were both associated with better survival whereas having a co-resident grandfather was associated with lower chance to survive for infants (age &lt; 1 year). Separating the effect between maternal and paternal grandparents and grandmothers and grandfathers revealed no differences in the effects between lineages. Negative effect of having a co-residing grandfather was not significant when grandfathers were separated for lineage specific models. These results implicate that accounting for the co-residence status and child’s age, grandparents were mostly beneficial when not co-residing with very young children and that having a co-residing grandfather at that age could be associated with lower chances to survive. Predictions made by grandmother hypothesis and resource competition both received support. The results presented here also offered comparison points to preindustrial and contemporary three-generational families.

Matrilateral bias of grandparental investment in grandchildren persists despite the grandchildren's adverse early life experiences

Evolutionary theory predicts a downward flow of investment from older to younger generations, representing individual efforts to maximize inclusive fitness. Maternal grandparents and maternal grandmothers (MGMs) in particular consistently show the highest levels of investment (e.g. time, care and resources) in their grandchildren. Grandparental investment overall may depend on social and environmental conditions that affect the development of children and modify the benefits and costs of investment. Currently, the responses of grandparents to adverse early life experiences (AELEs) in their grandchildren are assessed from a perspective of increased investment to meet increased need. Here, we formulate an alternative prediction that AELEs may be associated with reduced grandparental investment, as they can reduce the reproductive value of the grandchildren. Moreover, we predicted that paternal grandparents react more strongly to AELEs compared to maternal grandparents because maternal kin should expend extra effort to invest in their descendants. Using population-based survey data for English and Welsh adolescents, we found evidence that the investment of maternal grandparents (MGMs in particular) in their grandchildren was unrelated to the grandchildren's AELEs, while paternal grandparents invested less in grandchildren who had experienced more AELEs. These findings seemed robust to measurement errors in AELEs and confounding due to omitted shared causes.

Predictors of Social Media Use in Two Family Generations

Older adults have recently begun to adopt social media in increasing numbers. Even so, little is known about the factors influencing older adults' social media adoption. Here, we identify factors that predict the use of social media among older adults (aged 68-73) and compare them to those of their adult children (aged 19-56) using population-based data from Finland. As predictors for social media use, we utilized demographic factors as well as characteristics of the respondents' social lives. In addition, we test whether social media use in older adults is predicted by the social media use of their adult children. The data used in this study uniquely enable the study of this question because actual parent-child dyads are identifiable. In both generations, women and those with higher education were more likely to use social media. Predictors specific to men of the older generation were being divorced and younger, and predictors specific to women of the older generation were having better health and more frequent contact with friends. A higher number of children predicted use in both men and women in the older generation. As for the younger generation, specific predictors for social media use in women were younger age, divorce, higher number of children, and more frequent contact with friends. For men in the younger generation, there were no significant predictors for social media use besides higher education, which predicted social media use in all groups. Finally, social media use in a parent representing the older generation was predicted by the social media use of their adult children. This study provides novel information on the predictors of the use of social media in two family generations.

Grandparenting, health, and well-being: a systematic literature review

Whether grandparenting is associated with improved health or well-being among older adults is a salient question in present-day aging societies. This systematic review compiles studies that consider the health or well-being outcomes of grandparenting, concerning (1) custodial grandparent families, where grandparents are raising grandchildren without parental presence; (2) three-generation households, where grandparents are living with adult children and grandchildren; and (3) non-coresiding grandparents, who are involved in the lives of their grandchildren. Review was based on literature searches conducted in September 2019 via Web of Science, PubMed, PsycINFO, and Ebsco. We screened 3868 abstracts across four databases, and by following the PRISMA guidelines, we identified 92 relevant articles (117 studies) that were published between 1978 and 2019. In 68% of cases, custodial grandparenting was associated with decreased health or well-being of grandparents. The few studies considering the health or well-being of grandparents living in three-generation households provided mixed findings (39% positive; 39% negative). Finally, in 69% of cases, involvement of non-coresiding grandparents was associated with improved grandparental outcomes; however, there was only limited support for the prediction that involved grandparenting being causally associated with grandparental health or well-being. Despite this, after different robustness checks (counting all nonsignificant results, taking into account the representativeness of the data and causal methodology), the main finding remains the same: the most negative results are found among custodial grandparents and three-generation households and most positive results among non-coresiding grandparents.

Does Transition to Retirement Promote Grandchild Care? Evidence From Europe

Evolutionary theory posits that grandparents can increase their inclusive fitness by investing in their grandchildren. This study explored whether the transition to retirement affected the amount of grandchild care that European grandparents provided to their descendants. Data from five waves of the longitudinal Survey of Health, Aging, and Retirement in Europe collected between 2004 and 2015 from 15 countries were used. We executed within-person (or fixed-effect) regression models, which considered individual variations and person-specific changes over time. It was detected that transition to retirement was associated with increased grandchild care among both grandmothers and grandfathers. However, the effect of retirement was stronger for grandfathers than for grandmothers. Moreover, transition to retirement was associated with increased grandchild care among both maternal and paternal grandparents, but there was no significant difference between lineages in the magnitude of the effect of transition to retirement on grandchild care. In public debate retirees are often considered a burden to society but the present study indicated that when grandparents retire, their investment in grandchildren increased. The findings are discussed with reference to key evolutionary theories that consider older adults' tendency to invest time and resources in their grandchildren.

Does Parental Investment Shape Adult Children's Fertility Intentions? Findings From a German Family Panel

Parents can play an important role in the childbearing plans of adult children. However, studies testing whether changes in parental investment are associated with subsequent changes in fertility intentions over time are lacking. We investigated whether parental investment, measured as contact frequency, emotional closeness, financial support, and childcare, is associated with adult children's intentions to have a first and a second, or subsequent, child within the next 2 years. These associations were studied in four different parent-adult child dyads based on the sex of parents and adult children (i.e, mother-daughter, mother-son, father-daughter, father-son). The participants are from the German Family Panel, which is a longitudinal survey of younger and middle-aged adults with eight follow-up waves. We exploited within-person (or fixed-effect) regression models, which concentrated an individual's variation over time (i.e., whether changes in parental investment frequencies are associated with subsequent changes in adult children's fertility intentions). It was detected that increased emotional closeness between fathers and daughters was associated with increased adult daughter's intentions to have a first child but father-daughter contact decreased daughter's intentions to have another child, and maternal financial support decreased son's intentions to have a first child. Overall, statistically nonsignificant associations outweighed significant ones. Although it is often assumed that parental investment is an important factor influencing the childbearing decisions of adult children, the present findings indicate that parental investment may not increase adult children's intentions to have a/another child in Germany.

Short-term reciprocity between adult children and parents: A within-person investigation of longitudinal data

Although reciprocity of intergenerational support has been widely considered in family studies, empirical investigations utilizing panel data are still rather scarce. This study used data from four waves of the German Family Panel (pairfam), which were collected in two-year intervals between 2009 and 2016. We examined whether the frequency of received support from parents previously is associated with the frequency of provided support to parents later. Multiple forms of support were considered that may be used as currencies of intergenerational exchange (i.e., one could be exchanged for another): emotional support, practical help, financial aid and personal care. Our analyses used multilevel regression models and investigated both between- and within-person effects. Between-person effects indicated mainly positive associations between different forms of received and provided support. However, these associations were confirmed by only a few of the within-person effects, which examined individuals' variations over time. According to within-person effects, an increase in the frequency of emotional support that a son received from a parent was positively associated with subsequent provision of financial support for that parent. Additionally, an increase in the frequency of practical help that daughters received from their fathers was positively associated with subsequent provision of financial aid to their fathers. The magnitude of these positive within-person effects was smaller compared to the between-person effects. Within-person effects did not provide further evidence for causal intergenerational reciprocity within the investigated time period.

Grandparental Childcare for Biological, Adopted, and Step-Offspring: Findings From Cross-National Surveys

Based on kin selection theory, amounts of grandparental investment should reflect the probability to share common genes with offspring. Adoption may represent a special case, however, yet grandparental investment in adopted children has previously been both theoretically misconstrued and little investigated. Here, we study for the first time how grandparental childcare provision is distributed between biological, adopted, and step-offspring. Using Generations and Gender Surveys (n = 15,168 adult child-grandmother and 12,193 adult child-grandfather dyads) and the Survey of Health, Ageing, and Retirement in Europe (n = 17,233 grandmother-adult child and 13,000 grandfather-adult child dyads), we find that grandparents were less likely to provide care to stepchildren than to adopted and biological children, but no difference between adopted and biological children. These findings were present in both data sets and for both grandmothers and grandfathers, after several potentially confounding factors were taken into account. The stepchild disadvantage is in line with kin selection theory. The congruent amounts of care provided to adopted and biological children may reflect similar levels of adult-child attachment, selection effects, and greater need in adoptive families, as well as some degree of genetical relatedness in the case of kin adoption. The study provides new evidence of biased kin investments in contemporary societies and stresses the importance of psychological motivation and attachment in evolutionary studies of kin investment.

Transition to Grandparenthood and Subjective Well-Being in Older Europeans: A Within-Person Investigation Using Longitudinal Data

The transition to grandparenthood, that is the birth of the first grandchild, is often assumed to increase the subjective well-being of older adults; however, prior studies are scarce and have provided mixed results. Investigation of the associations between grandparenthood and subjective well-being, measured by self-rated life satisfaction, quality of life scores, and depressive symptoms, used the longitudinal Survey of Health, Ageing and Retirement in Europe from 13 countries, including follow-up waves between 2006 and 2015 (n = 64,940 person-observations from 38,456 unique persons of whom 18,207 had two or more measurement times). Both between-person and within-person (or fixed-effect) regression models were executed, where between-person associations represent results across individuals, that is, between grandparents and non-grandparents; within-person associations represent an individual's variation over time, that is, they consider whether the transition to grandparenthood increases or decreases subjective well-being. According to the between-person models, both grandmothers and grandfathers reported higher rate of life satisfaction and quality of life than non-grandparents. Moreover, grandmothers reported fewer depressive symptoms than women without grandchildren. The within-person models indicated that entry into grandmotherhood was associated with both improved quality of life scores and improved life satisfaction. These findings are discussed with reference to inclusive fitness theory, parental investment theory, and the grandmother hypothesis.

Grandparental childcare, health and well-being in Europe: A within-individual investigation of longitudinal data

Previous studies suggest grandparental childcare is associated with improved health and well-being of grandparents but limited information on the causal nature of this association exists. Here, we use the longitudinal Survey of Health, Ageing and Retirement in Europe (SHARE) of people aged 50 and above across 11 countries including follow-up waves between 2004 and 2015 (n = 41,713 person-observations from 24,787 unique persons of whom 11,102 had two or more measurement times). Between-person and within-person (or fixed-effect) regressions were applied, where between-person models show associations across participants and within-person models focus on each participant's variation over time. Health and well-being were measured according to self-rated health, difficulties with activities of daily living (ADLs), depressive symptoms, life satisfaction and meaning of life scores. Across all analyses, childcare assistance provided by older adults to their adult children, was associated with increased health and well-being of grandparents. However, these associations were almost completely due to between-person differences and did not hold in within-person analyses that compared the same participants over time. Fewer ADL limitations for grandparents who provided childcare assistance was the only association that remained in the within-individual analyses. These findings suggest that there might be only limited causal association between grandchild care and grandparental well-being and that it may be specific to physical rather than cognitive factors. The results are discussed with regard to evolutionary psychology assumptions of altruistic behavior and positive health outcomes for the helper.

Multigenerational Effects on Children's Cognitive and Socioemotional Outcomes: A Within-Child Investigation

Associations between grandparental investment and child outcomes were investigated using three waves of a longitudinal British Millennium Cohort Study that included children between the ages of 9 months and 5 years (n = 24,614 person-observations from 13,744 children). Grandparental investment was measured by parent-grandparent contact frequency and grandparental financial support. Child cognitive development was measured using the British Ability Scale and socioemotional outcomes using the Strength and Difficulties Questionnaire. Grandparental investment was associated with improved cognitive and socioemotional outcomes among children. However, these associations occurred because of between-person effects and did not exist in within-person analyses that compared the same children over time. The results are discussed in terms of their contribution to multigenerational relationships research.

Intergenerational relations before and after offspring arrive: A within-person investigation

The birth of a child may re-orientate the relations between adult children and their parents; however, the previous studies on the topic are both scarce and methodologically limited. The current study investigates whether younger adults' entry into parenthood (i.e., the birth of the first child) is associated with increased contact frequency, emotional closeness, intimacy and conflict with their own parents. The participants are from the German Panel Analysis of Intimate Relationships and Family Dynamics, which is a prospective survey of younger adults with six annual follow-up waves between 2009 and 2014 (n = 17,662 person-observations from 4821 persons). Within-person regression with a focus on each individual's variation over time was used to detect changes in intergenerational relations. The contact frequency between daughters and mothers increased after the arrival of their first child. In contrast, the emotional closeness and intimacy between sons and mothers decreased after the birth of their first child. The results are discussed with reference to gender-based differences in intergenerational relations.

Intergenerational relations and child development in England

Evolutionary studies have shown that in many traditional populations the beneficial effects of grandparental presence for grandchildren may vary according to the sex and lineage of the grandparents, as well as by the sex of the grandchild. However, few studies have investigated the relevance of these factors in modern developed societies. The present investigation uses the Millennium Cohort Study (n = 4,636 children) to analyse the association between grandparental investment and child development in contemporary England. Grandparental investment is measured by parent-grandparent contact frequencies at the child’s age of 3 and child development by “early learning goals” over the first year of primary school assessed with the Foundation Stage Profile (FSP). Children whose mothers reported contacts with maternal grandparents receive higher FSP scores compared to those with no contact at all. In addition, children whose fathers reported daily contacts with paternal grandfathers have lower FSP scores than other children. The study provides evidence of the relevance of grandparental investment on grandchild development also in developed societies. The results are discussed with reference to the grandmother hypothesis, sex-specific reproductive strategies and sex chromosome hypothesis.

Parental Resources, Sibship Size, and Educational Performance in 20 Countries: Evidence for the Compensation Model

We study whether having several siblings decreases the level of educational performance of adolescents and whether this phenomenon can be compensated by other factors such as the economic or cultural resources of the parents. Based on this compensation model, parental resources should be associated with children's educational attainments more strongly in families with a higher rather than a lower number of children. We analyzed the Program for International Student Assessment (PISA) data from 20 Western countries and found that better family wealth, an increased level of parental education, and a higher parental occupational status were associated with increased educational attainments more strongly among 15-year-old children who have siblings than among children without siblings. The same effect was not found in the case of family cultural possessions. Although parental resources may matter more in larger families than in smaller families, some types of resources are more important than others regarding compensation.

More Unintended Injuries in Half Sibling Than Full Sibling Households in the UK

Sibling relationships can be a source of both support and conflict. Due to more severe sibling competition, childhood injuries are predicted to increase as genetic relatedness decreases. Here we use the British Millennium Cohort Study (n = 7,143 children) to analyze the risk of accidents for small children in different types of households. Results show that, after controlling for several potential confounding factors, 3-year-old children who lived in same household with their full siblings had a significantly lower risk of injuries (predicted probability 25.3%) than did children who lived with both their full and half siblings (29.6%) or only with their half siblings (29.1%). We conclude that efforts to prevent child maltreatment should pay attention to sibling relations and family composition.

The association between unequal parental treatment and the sibling relationship in Finland: The difference between full and half-siblings

Studies have shown that unequal parental treatment is associated with relationship quality between siblings. However, it is unclear how it affects the relationship between full and half-siblings. Using data from the Generational Transmissions in Finland project (n = 1,537 younger adults), we study whether those who have half-siblings perceive more unequal parental treatment than those who have full siblings only. In addition, we study how unequal parental treatment is associated with sibling relationship between full, maternal, and paternal half-siblings. First, we found that individuals who have maternal and/or paternal half-siblings are more likely to have encountered unequal maternal treatment than individuals who have full siblings only. Second, we found that unequal parental treatment impairs full as well as maternal and paternal half-sibling relations in adulthood. Third, unequal parental treatment mediates the effect of genetic relatedness on sibling relations in the case of maternal half-siblings, but not in the case of paternal half-siblings. After controlling for unequal parental treatment, the quality of maternal half-sibling relationships did not differ from that of full siblings, whereas the quality of paternal half-sibling relationships still did. Fourth, the qualitative comments (n = 206) from the same population reveal that unequal parental treatment presents itself several ways, such as differential financial, emotional, or practical support.

Multi-partner fertility is associated with lower grandparental investment from in-laws in Finland

Divorce and remarriage influence family relations, yet few studies explore changes in grandparenting due to family recomposition. We study variations in grandparental investment when the parents have children from several unions. Using nationally representative data of younger adults from the Generational Transmissions in Finland survey conducted in 2012 (sample n = 760 parents), we compare the grandchild care that parents report having received from their parents and parents-in-law. Results show that multipartner fertility is not associated with the amount of grandparental investment a parent receives from his or her own parents, but is associated with the investment received from mother's parents-in-law. Mother's parents-in-law are less likely to invest in grandchild sets which include step-grandchildren, compared to grandchildren living with their original parents. Fully biological grandchildren are 31% more likely to receive grandparental care compared to grandchild sets including step grandchildren. Thus the reduction in grandparental investment associated with step-grandchildren may also affect children from the new union.

The association between grandmaternal investment and early years overweight in the UK

Previous studies show that in many pre-modern and traditional populations the presence of a grandmother correlates with increased child survival rates, maybe as a result of improved child nutrition. Grandmaternal investment aimed at improving grandchildren's nutritional status in subsistence societies may have different outcomes in contemporary affluent societies. Using the British Millennium Cohort Study I investigate the association between maternal and paternal grandmothers' childcare and early years overweight in the UK. Results show that children who were cared for mainly by their grandmothers between the ages of 9 months and 3 years were more likely overweight at age 3 than children who were cared for by their parents. My results are in line with Pearce, Abbas, Ferguson, Graham, and Law (2010), although they did not distinguish grandmothers by lineage. Grandmothers may influence children's nutritional status in contemporary societies, but as with many evolved behavioral strategies the outcome may be no longer beneficial.

The Association between Grandmaternal Investment and Early Years Overweight in the UK

Previous studies show that in many pre-modern and traditional populations the presence of a grandmother correlates with increased child survival rates, maybe as a result of improved child nutrition. Grandmaternal investment aimed at improving grandchildren's nutritional status in subsistence societies may have different outcomes in contemporary affluent societies. Using the British Millennium Cohort Study I investigate the association between maternal and paternal grandmothers' childcare and early years overweight in the UK. Results show that children who were cared for mainly by their grandmothers between the ages of 9 months and 3 years were more likely overweight at age 3 than children who were cared for by their parents. My results are in line with Pearce, Abbas, Ferguson, Graham, and Law (2010) , although they did not distinguish grandmothers by lineage. Grandmothers may influence children's nutritional status in contemporary societies, but as with many evolved behavioral strategies the outcome may be no longer beneficial.

Adolescent grandchildren's perceptions of grandparents' involvement in UK: an interpretation from life course and evolutionary theory perspective

In this article, we study grandparental involvement from the viewpoint of evolutionary theory and sociological life course perception. We have used 'the Involved Grandparenting and Child Well-Being 2007' survey, which is the first nationally representative sample of British and Welsh adolescents aged 11-16 (n = 1,488). First, we explore with the descriptive statistics the amount of grandparental involvement reported by adolescents. The result follows the predicted pattern: maternal grandparent is reported to involve in a grandchild's life the most, second maternal grandfather, third paternal grandmother and the last paternal grandfather. Second, we focus more closely on separate grandparents and show with four linear regression models which factors are connected to each grandparent's involvement. Grandchild's age, grandparent's health, grandparent's labour force participation and distance between a grandparent and a grandchild were factors that have similar effects in relation to all grandparents. Marital status mattered only for grandfathers, whereas family structure of a grandchild has opposite effects in relation to maternal and paternal grandparents. Grandchild's sex, grandparent's age, the number of grandchildren and the number of living grandparents all mattered, but only with respect to some grandparents. The study shows that it is advantageous to merge sociological and evolutionary viewpoints when studying a grandparental involvement in a modern society.

Grandparental child care in Europe: evidence for preferential investment in more certain kin

Theories of kin selection and parental investment predict stronger investment in children and grandchildren by women and maternal kin. Due to paternity uncertainty, parental and grandparental investments along paternal lineages are based on less certain genetic relatedness with the children and grandchildren. Additionally, the hypothesis of preferential investment (Laham, Gonsalkorale, and von Hippel, 2005) predicts investment to vary according to available investment options. Two previous studies have tested this hypothesis with small samples and conflicting results. Using the second wave of the large and multinational Survey of Health, Ageing and Retirement in Europe (SHARE), collected in 2006-07, we study the preferential investment hypothesis in contemporary Europe based on self-reported grandparental provision of child care. We predict that 1) maternal grandmothers provide most care for their grandchildren, followed by maternal grandfathers, paternal grandmothers and last by paternal grandfathers; 2) maternal grandfathers and paternal grandmothers provide equal amounts of care when the latter do not have grandchildren via a daughter; 3) women who have grandchildren via both a daughter and a son will look after the children of the daughter more; and 4) men who have grandchildren via both a daughter and a son will look after the children of the daughter more. Results support all four hypotheses and provide evidence for the continuing effects of paternity uncertainty in contemporary kin behavior.

Grandparental Child Care in Europe: Evidence for Preferential Investment in More Certain Kin

Theories of kin selection and parental investment predict stronger investment in children and grandchildren by women and maternal kin. Due to paternity uncertainty, parental and grandparental investments along paternal lineages are based on less certain genetic relatedness with the children and grandchildren. Additionally, the hypothesis of preferential investment (Laham, Gonsalkorale, and von Hippel, 2005) predicts investment to vary according to available investment options. Two previous studies have tested this hypothesis with small samples and conflicting results. Using the second wave of the large and multinational Survey of Health, Ageing and Retirement in Europe (SHARE), collected in 2006–07, we study the preferential investment hypothesis in contemporary Europe based on self-reported grandparental provision of child care. We predict that 1) maternal grandmothers provide most care for their grandchildren, followed by maternal grandfathers, paternal grandmothers and last by paternal grandfathers; 2) maternal grandfathers and paternal grandmothers provide equal amounts of care when the latter do not have grandchildren via a daughter; 3) women who have grandchildren via both a daughter and a son will look after the children of the daughter more; and 4) men who have grandchildren via both a daughter and a son will look after the children of the daughter more. Results support all four hypotheses and provide evidence for the continuing effects of paternity uncertainty in contemporary kin behavior.