Data relating to change in locus of control orientation of parents overtime (from pre-birth to 20 years later), participating in the Avon Longitudinal Study of Parents and Children (ALSPAC)

Locus of control (LOC) measures an individual׳s expectancy regarding their ability to affect what happens to them based on their behavior. Those with an internal LOC (ILOC) believe their own behavior influences what happens to them. Those with an external LOC (ELOC) perceive that what happens to them is beyond their control (i.e. determined by luck, fate, chance or powerful others) [1]. A vast amount of research (mainly cross-sectional) suggests that an ELOC is associated with many adverse personal, social, academic and health outcomes. LOC data were uniquely collected prenatally from over 12,000 pregnant women and their partners enrolled in the Avon Longitudinal Study of Parents and Children (ALSPAC). The LOC measure used was a shortened version of the adult version of the Nowicki-Strickland Internal-External locus of control scale. This was administered to the mothers within self-completion questionnaires at three-time points: during pregnancy, at 6 and at 18 years post-partum. In parallel, self-completion questionnaires containing the same LOC questions were completed by their partners during pregnancy, at 6 and 20 years later. ALSPAC LOC data are unique in that they measured orientation over time and on a much larger sample of respondents than is usual. We describe the scale used, why it was chosen and how individual scores changed over time.

Total mercury exposure in early pregnancy has no adverse association with scholastic ability of the offspring particularly if the mother eats fish

There is a public perception that relatively low doses of mercury found in seafood are harmful to the fetal brain but little consistent evidence to support this. In earlier publications we have shown no adverse associations between maternal total blood mercury levels and child behaviour, early development or cognitive function as measured by IQ. However, for IQ the lack of adverse association was conditional upon the mother being a fish eater. In this paper we analyse further data from the Avon Longitudinal Study of Parents and Children (ALSPAC), this time examining whether prenatal exposure to total mercury is associated with the child's scholastic abilities in reading, spelling, phoneme awareness, mathematics and science; the number of participants with prenatal mercury and relevant test results varied from 1500 to 2200. Multiple regression was used to assess relationships between prenatal total blood mercury concentrations and 16 different test results, after taking account of a variety of potential confounders; in parallel, logistic regression was used to determine associations with the risk of the child being in the lowest 15% of each score. Analyses were repeated stratifying for fish consumption and sex of the child. There was no evidence of harm associated with the level of total mercury, provided the mother ate fish during pregnancy. This was particularly true for tests of mathematics and science. We conclude that women should be confident that eating fish in pregnancy is beneficial for their unborn child.

Events associated with stability and change in adult locus of control orientation over a six-year period

Although locus of control (LOC) has been the focus of thousands of studies we know little about how or if it changes over time and what is associated with change. Our lack of knowledge stems in part from the past use of cross-sectional and not longitudinal methodologies to study small numbers of participants from non-representative populations. The purpose of the present study was to use a longitudinal design with a large representative population to provide relevant information concerning the stability and change of adult LOC. Before the birth of their child, and again six years later, mothers and their partners participating in the Avon Longitudinal Study of Parents and Children (ALSPAC) completed LOC tests and structured stressful events surveys. Analyses revealed that stresses experienced in relationships with spouses, friends and family, financial stability and job security, and illness/smoking were associated with changes in LOC. Results suggest substantial variation of LOC within spousal/parent dyads and moderate stability of LOC over time for both men and women. Stressors associated with change in LOC may be possible candidates when considering interventions to modify LOC expectancies.

Prenatal mercury exposure and features of autism: a prospective population study

Background

Mercury (Hg) has been suspected of causing autism in the past, especially a suspected link with vaccinations containing thiomersal, but a review of the literature shows that has been largely repudiated. Of more significant burden is the total quantity of Hg in the environment. Here, we have used the Avon Longitudinal Study of Parents and Children (ALSPAC) to test whether prenatal exposure from total maternal blood Hg in the first half of pregnancy is associated with the risk of autism or of extreme levels of autistic traits. This is the largest longitudinal study to date to have tested this hypothesis and the only one to have considered early pregnancy.

Methods

We have used three strategies: (1) direct comparison of 45 pregnancies resulting in children with diagnosed autism from a population of 3840, (2) comparison of high scores on each of the four autistic traits within the population at risk (n~2800), and (3) indirect measures of association of these outcomes with proxies for increased Hg levels such as frequency of fish consumption and exposure to dental amalgam (n > 8000). Logistic regression adjusted for social conditions including maternal age, housing circumstances, maternal education, and parity. Interactions were tested between risks to offspring of fish and non-fish eaters.

Results

There was no suggestion of an adverse effect of total prenatal blood Hg levels on diagnosed autism (AOR 0.89; 95% CI 0.65, 1.22) per SD of Hg (P = 0.485). The only indication of adverse effects concerned a measure of poor social cognition when the mother ate no fish, where the AOR was 1.63 [95% CI 1.02, 2.62] per SD of Hg (P = 0.041), significantly different from the association among the offspring of fish-eaters (AOR = 0.74 [95% CI 0.41, 1.35]).

Conclusion

In conclusion, our study identifies no adverse effect of prenatal total blood Hg on autism or autistic traits provided the mother ate fish. Although these results should be confirmed in other populations, accumulating evidence substantiates the recommendation to eat fish during pregnancy.

Electronic supplementary material

The online version of this article (10.1186/s13229-018-0215-7) contains supplementary material, which is available to authorized users.

Are the early childhood antecedents of men’s external locus of control similar to those of their female partners?

Background: The concept of locus of control of reinforcement was introduced by Julian Rotter and has been the focus of intense research for nearly half a century.  Surprisingly little research has been directed at clarifying antecedents of locus of control (LOC) orientations in adult men apart from a few small studies. We previously identified a number of independent antecedents associated with women’s LOC, including features of their parents and early childhood. This raised the question as to whether these factors were also associated with the development of LOC in men. Methods: To identify antecedents of LOC orientations in a representative population of women we previously analysed information concerning characteristics of their parents and their own childhood experiences using pregnant women taking part in the Avon Longitudinal Study of Parents and Children (ALSPAC).  Here we use the same design to determine whether their male partners have similar antecedents of LOC orientation. As previously, we use a hypothesis-free exposome technique using all available information on the parents and childhood of the individuals. Results: We show that men had many of the same antecedent characteristics as the women – in particular, their mother’s year of birth and father’s social group, being exposed to cigarette smoke prenatally, starting to smoke regularly before the age of 11, and having a friend die were all associated with being external. Associations of internality common to both were warm maternal care, being breast fed, being born in an area other than that where they currently live, attending boarding school and having a parent admitted to hospital. Conclusions: In general, the antecedents of male external and internal personalities have many similarities to those of women, thus providing some features to inform the possible theoretical background as to how LOC might develop over time.

Parental External Locus of Control in Pregnancy Is Associated with Subsequent Teacher Ratings of Negative Behavior in Primary School: Findings from a British Birth Cohort

The purpose of the present study was to examine whether parents' locus of control (LOC) obtained before the birth of their child predicts the child's behavior at school in School Years 3 (ages 7-8) and 6 (ages 10-11). A modified version of the adult Nowicki-Strickland internal-external locus of control scale was completed by mothers and fathers in their own home during pregnancy. Externality was defined as a score greater than the median and internality as equal to, or less than, the median. Outcomes were the five individual subscales and the total difficulties of Goodman's strengths and difficulties' questionnaire completed by the children's class teachers at the end of School Years 3 and 6. As predicted, it was found that the greater the presence of externality in the parents, the greater the increased risk of the child's adverse behavior as rated by teachers. The risk was generally greatest if both parents were external and lowest if both were internal. There was a consistent relationship at both Year 3 and Year 6 between maternal externality in pregnancy and children's emotional difficulties. However, for other behaviors, the pattern of associations varied depending on whether the mother or father was external, the type of adverse behavior, and the School Year in which children were assessed. Prenatal parental externality appears to be significantly associated with a variety of children's negative behaviors. Of note was the finding that fathers' as well as mothers' LOC was important in determining children's outcomes. Implications of the complexity of the results for the role parents may play in children's personality and adjustment are discussed.

The mid-childhood and adolescent antecedents of women's external locus of control orientation

Background: External locus of control orientation (ELOC) is a powerful predictor of adverse consequences in regard to health, educational attainment, inter-personal relationships and well-being. Although many cross-sectional studies have been carried out, relatively little is known about antecedent factors influencing the development of ELOC. Methods: Over 12,000 pregnant women who enrolled in the Avon Longitudinal Study of Parents and Children (ALSPAC) in south-west England, had completed a brief version of the Adult Nowicki-Strickland Internal-External LOC scale, together with detailed questions concerning their own parents and childhood.  A series of hypothesis-free structured backwards stepwise logistic regression analyses used an exposome approach with ELOC as the outcome. Results: Significant positive associations were found with smoking of the parents of the surveyed women, including prenatal exposure, and their own onset of regular smoking in mid-childhood (6-11 years). Increased odds of ELOC were also found with the absence of their fathers in early childhood, presence of older siblings, and with being born and brought up in the same area as they resided in at the time surveyed. Protective influences in the surveyed women included positive rating of their mother's care, having a relatively educated mother, attending boarding school, their own age (the older they were, the less likely were they to have an external orientation), having a mentally ill parent, a sibling hospitalized or a relative die. Conclusions: There are two conclusions: (i) that not all stressful events contribute to the development of ELOC and it would be essential for models of antecedents of ELOC to take note of this complexity, and (ii) there are consistent (albeit unexpected) findings that highlight associations with cigarette smoke exposure of the woman from fetal life through to when starting to smoke regularly herself in mid-childhood. It is important that these findings are tested in other populations.

The mid-childhood and adolescent antecedents of women's external locus of control orientation

Background: External locus of control orientation (ELOC) is a powerful predictor of adverse consequences in regard to health, educational attainment, inter-personal relationships and well-being. Although many cross-sectional studies have been carried out, relatively little is known about antecedent factors influencing the development of ELOC. Methods: Over 12,000 pregnant women who enrolled in the Avon Longitudinal Study of Parents and Children (ALSPAC) in south-west England, had completed a brief version of the Adult Nowicki-Strickland Internal-External LOC scale, together with detailed questions concerning their own parents and childhood.  A series of hypothesis-free structured backwards stepwise logistic regression analyses used an exposome approach with ELOC as the outcome. Results: Significant positive associations were found with smoking of the parents of the surveyed women, including prenatal exposure, and their own onset of regular smoking in mid-childhood (6-11 years). Increased odds of ELOC were also found with the absence of their fathers in early childhood, presence of older siblings, and with being born and brought up in the same area as they resided in at the time surveyed. Protective influences in the surveyed women included positive rating of their mother's care, having a relatively educated mother, attending boarding school, their own age (the older they were, the less likely were they to have an external orientation), having a mentally ill parent, a sibling hospitalized or a relative die. Conclusions: There are two conclusions: (i) that not all stressful events contribute to the development of ELOC and it would be essential for models of antecedents of ELOC to take note of this complexity, and (ii) there are consistent (albeit unexpected) findings that highlight associations with cigarette smoke exposure of the woman from fetal life through to when starting to smoke regularly herself in mid-childhood. It is important that these findings are tested in other populations.

Prenatal Internal Locus of Control Is Positively Associated with Offspring IQ, Mediated through Parenting Behavior, Prenatal Lifestyle and Social Circumstances

Locus of control (LOC) is a measure that identifies the likelihood as to whether an individual considers what happens to him is largely a matter of luck or fate (known as externally oriented) or whether it is something that the individual can influence (internality). Here we have used data collected as part of the Avon Longitudinal Study of Parents and Children (ALSPAC) to determine the associations between the mothers’ LOC orientation before the birth of the child and her child’s cognition measured at age 8. Using results from 6801 children we show that maternal internal LOC is associated with increased ability in offspring IQ, as measured using the WISC, with children of internally oriented mothers having an advantage of approximately 7 IQ points at age 8. As a sensitivity analysis we used the IQ test results of a sample of 986 preschool children tested using the WPSSI at age 4. A similar advantage was found among the offspring of the internally oriented mothers. We investigated mechanistic explanations for these results firstly by determining the extent to which three separate sets of factors known to be influenced by the LOC orientation might explain these findings. We showed that (a) perinatal life-style exposures, (b) parenting attitudes and strategies and (c) socio-economic circumstances, largely explain the mechanism through which the internality of the mother influences the cognition of the child. Similar effects were found using the smaller sample tested at age 4. The results indicate that efforts made to foster internality in adolescents and young adults prior to parenthood may result in improvements in the cognitive development of the next generation. Intervention studies are urgently needed.

Maternal prenatal blood mercury is not adversely associated with offspring IQ at 8 years provided the mother eats fish: A British prebirth cohort study

Background

Conflicting evidence concerning possible harm from mercury (Hg) in regard to offspring cognition if the woman eats fish has prompted this study to examine evidence from a British pre-birth cohort to investigate the relationship between the two.

Methods

Pregnant women (median prenatal blood mercury 1.86 μg/L) resident in the study area with delivery between April 1991 and December 1992 were followed up and verbal, performance and total intelligence quotient (IQ) of 2062 offspring were measured at age 8. Analysis treated IQ as (a) continuous and (b) the lowest 25% of the distribution. Multiple and logistic regression analyses took account of social and demographic variables. Stratification considered children of fish eaters separately.

Results

Before adjustment, mean full-scale IQ increased with increasing Hg (change with 1SD of Hg = +2.02; 95%CI +1.40,+2.64 IQ points; P < 0.0001); after adjustment effect size was reduced although still positive (+0.61;95%CI -0.06,+1.29 IQ points; P = 0.073). The adjusted positive relationship was stronger when fish-eating mothers were considered separately (+0.84:95%CI +0.13,+1.56 IQ points; P = 0.021) in comparison with the outcomes for non-fish eaters, where the adjusted relationship was negative (-2.22;95%CI -5.00,+0.56 IQ points; P = 0.117). The binary outcome showed a similar pattern with the adjusted OR for non-fish-eaters 1.79 (95%CI 1.10,2.93; P = 0.019) per SD of Hg, significantly different from that for fish consumers (0.94;95%CI:0.82,1.08)(P_interaction<0.05). There were no differences between the sexes in the associations, nor did the level of the mother’s blood selenium change the effect sizes.

Conclusion

The relationship between intrauterine exposure to mercury and offspring IQ appears to be benign provided the mother consumes fish.

The Impact of Prenatal Parental Locus of Control on Children's Psychological Outcomes in Infancy and Early Childhood: A Prospective 5 Year Study

Locus of control is one of the most widely studied concepts in the history of personality psychology. In spite of its popularity and its associations with numerous relevant outcomes, the ability of locus of control to predict future behaviors involving parenting effectiveness has been under researched. The few parent locus of control children's outcome studies are characterized by cross-sectional methodologies that focus on mothers. The present study uses a prospective methodology to compare data on mothers' and fathers' locus of control with their child's behavior outcomes from a large scale research project, the Avon Longitudinal Study of Parents and Children (ALSPAC). Based on Rotter's Social Learning Theory published in 1954 and past empirical research, it was predicted and found that parent internality was associated with more positive child outcomes than parent externality. More specifically, when both parents were internal, their children had more positive outcomes in sleeping, eating, and tantrum behavior as compared to any other parent locus of control combination. However external parents had a less restrictive attitude which appeared to have a more beneficial effect on picky eating. Results confirmed how important parent locus of control is in the lives of children. Based on the findings, researchers are urged to develop interventions to change advice to parents and promote more internal locus of control among parents.

The antecedents of women's external locus of control: Associations with characteristics of their parents and their early childhood

Locus of control (LOC) measures individuals' expectancies regarding their ability to affect what happens to them based on how they behave. The more they believe their behaviour has something to do with what happens to them the more internal they are. In contrast the more they perceive that what happens to them is beyond their control and determined by luck, fate, chance or powerful others the more external they are. Copious research findings suggest that external LOC (ELOC) is associated with many adverse personal, social, academic and health outcomes. In spite of its importance in so many areas of human behaviour relatively little is known about the features of the early background of individuals that contributes to these expectancies. This is the first in a number of studies that will suggest possible antecedents and consequences of having a high ELOC. The study takes advantage of the data collected in the Avon Longitudinal Study of Parents and Children (ALSPAC), which started by studying pregnancies in 1991-1992 of residents in an area of south-west England. Over 12000 of the women who enrolled during pregnancy completed a set of questions in mid-pregnancy from which an LOC score was computed. ELOC was defined as a score greater than the median. The relationships with characteristics of the women's parents and her early childhood (<6 years) are considered first as unadjusted odds ratios and then as adjusted after analysis using hierarchical sets of stepwise logistic regressions. The relative contributions to the women's ELOC was measured using a goodness-of-fit (GOF) measure. The analyses demonstrated the independent importance of maternal and paternal backgrounds as well as features of her early childhood (<6 years). The final model identified nine independent features (each with P < 0.0001): year of birth of her mother, maternal and paternal education levels, father smoked, mother smoked when pregnant, year of birth of study woman, the number of older siblings she had, whether her father was absent during this period, and whether she spent her childhood in the study area. In conclusion, the woman's LOC appears to be independently influenced by a number of characteristics which may give clues as to possible mechanisms-and how internality may be supported in the future. Subsequent papers will assess both whether features of later childhood influence the woman's LOC and whether the LOC of men in the study have similar antecedents.

Prenatal mercury exposure and offspring behaviour in childhood and adolescence

BACKGROUND

There is considerable discussion over the possible harm caused by fetal exposure to mercury, but evidence of such harm is contradictory at levels commonly found in populations with moderate intakes of fish. Further information is needed to inform debate and clarify policy recommendations.

MATERIAL

Data were collected prospectively for the Avon Longitudinal Study of Parents and Children (ALSPAC). Whole blood taken in the first half of pregnancy was assayed for mercury. The outcomes were offspring behavioural assessments collected using the Strengths and Difficulties Questionnaire at seven time points between ages 4 and 16-17 years; five were completed by the mother and two by the teacher. Socioeconomic and biological confounders were first taken into account; further analyses added maternal blood selenium. Separate analyses compared the relationships between prenatal mercury levels and behaviour traits treated as continuous measures in women who ate fish with those who ate no fish in order to determine whether the relationships differed; the hypothesis was that fish consumption had benefits on the brain and masked any mercury effects. In order to prevent Type II errors, the P value for significance was set at 0.10.

RESULTS

Prenatal mercury measurements and offspring behaviour results were available for between 2776 (at 47 months) to 1599 mother-child pairs (at 16-17 years). Even given a P value of 0.10, the number of significant results was no greater than expected apart from the relationships with peer problems at 4, 6 and 10-11 years where the relationships with prenatal mercury were negative (i.e. the greater the level of mercury the fewer the problems the child had with his/her peers). There were no significant differences between the associations with mercury found among the offspring of women who ate fish in pregnancy and those who did not, nor did adjustment for selenium make a difference.

CONCLUSIONS

There were no adverse effects of maternal prenatal mercury levels on the behaviour of the offspring. A similar lack of relationship was found when the analyses were confined to those offspring whose mothers had eaten fish in pregnancy, and no consistent differences were found between the fish and non-fish eaters.

Are prenatal mercury levels associated with subsequent blood pressure in childhood and adolescence? The Avon prebirth cohort study

OBJECTIVES

There have been conflicting data suggesting that prenatal mercury exposure is associated with adverse cardiovascular measures in children. We therefore analysed a large prospective population study to investigate whether prenatal mercury exposure might influence offspring blood pressure (BP) and heart rate adversely.

DESIGN

Prospective birth cohort.

SETTING

The Avon Longitudinal Study of Parents and Children (ALSPAC).

PARTICIPANTS

Maternal whole blood collected in the first half of pregnancy was assayed for mercury and selenium. The offspring were followed throughout childhood and adolescence.

OUTCOME MEASURES

Offspring resting BP and heart rates measured under standard conditions on six occasions between ages 7 and 17 years (numbers analysed: 1754 at 7 years to 1102 at 17).

RESULTS

Statistical analyses took account of various factors present in pregnancy, including family adversity, maternal age, parity, smoking and alcohol intake. Unadjusted and adjusted regression analyses assessed the relationship between maternal prenatal mercury levels and offspring resting systolic and diastolic BP, and heart rates. A final set of analyses took account of selenium. Each analysis was carried out for all offspring, those whose mothers had, and those that had not, consumed fish during pregnancy. Further analysis for all offspring ascertained whether there were significant interaction effects between the sexes. There was little evidence to suggest that prenatal mercury exposure resulted in a clinically important increase in offspring BP in the whole group, since no effect size for an increase of 1 SD of blood mercury level was >0.3 mm Hg. Only 1 association was significant at p<0.05 and therefore likely due to chance.

CONCLUSIONS

This study reveals no evidence to support the hypothesis that prenatal mercury exposure has adverse long-term effects on offspring BP or heart rates during childhood or adolescence.

Data relating to early child development in the Avon Longitudinal Study of Parents and Children (ALSPAC), their relationship with prenatal blood mercury and stratification by fish consumption

As part of the Avon Longitudinal Study of Parents and Children (ALSPAC), measures of early child development were collected using both hands-on expert assessment (on a random 10% sub-sample) by trained psychologists at 18 months using the Griffiths Mental Development Scales (Extended 0–8 years) and from detailed questionnaires completed by the study mothers on the whole cohort using assessments based on the Denver Developmental Screening Test. The development determined by the psychologists on the 10% subsample showed a correlation of 0.49 (R. Wilson, 2003) [9] with the developmental level estimated from the maternal report. Maternal reports were used to determine the associations between prenatal blood mercury levels and scores of social achievement, fine motor skills, gross motor skills and communication at various preschool ages. (For results, please see doi:10.1016/j.neuro.2016.02.006 [1].)

Associations between prenatal mercury exposure and early child development in the ALSPAC study

INTRODUCTION

There is evidence that high levels of mercury exposure to the pregnant woman can result in damage to the brain of the developing fetus. However there is uncertainty as to whether lower levels of the metal have adverse effects on the development of the infant and whether components of fish consumption and/or the selenium status of the woman is protective.

METHODS

In this study we analysed data from the Avon Longitudinal Study of Parents and Children (ALSPAC) (n=2875-3264) to determine whether levels of total blood mercury of pregnant women collected in the first half of pregnancy are associated with the development of the offspring at ages 6, 18, 30 and 42 months. The developmental measures used maternal self-reported scales for individual types of development (fine and gross motor, social and communication skills) and total scores. Multiple and logistic regression analyses treated the outcomes both as continuous and as suboptimal (the lowest 15th centile). The statistical analyses first examined the association of prenatal mercury exposure with these developmental endpoints and then adjusted each for a number of social and maternal lifestyle factors; finally this model was adjusted for the blood selenium level.

RESULTS

Total maternal prenatal blood mercury and selenium ranged from 0.17 to 12.76 and 17.0 to 324μg/L respectively. We found no evidence to suggest that prenatal levels of maternal blood mercury were associated with adverse development of the child, even when the mother had consumed no fish during pregnancy. In general, the higher the mercury level the more advanced the development of the child within the range of exposure studied. For example, the fully adjusted effect sizes for total development at 6 and 42 months were +0.51 [95%CI +0.05, +1.00] and +0.43 [95%CI +0.08, +0.78] points per SD of mercury. For the risk of suboptimal development the ORs at these ages were 0.90 [95%CI 0.80, 1.02] and 0.88 [95%CI 0.77, 1.02]. In regard to the associations between blood mercury and child development there were no differences between the mothers who ate fish and those who did not, thus implying that the benefits were not solely due to the beneficial nutrients in fish.

CONCLUSIONS

We found no evidence of adverse associations between maternal prenatal blood mercury and child development between 6 and 42 months of age. The significant associations that were present were all in the beneficial direction.

A review of environmental contributions to childhood motor skills

Although much of children's motor skills have a heredity component, at least half of the variance is likely to be influenced by the environment. It is important to ascertain features of the environment that are responsible so that toxins can be avoided, children at risk can be identified, and beneficial interventions initiated. This review outlines the results of published studies and recommends the areas where further research is required. We found much confusion with little comparability concerning the ages or measures used. Few studies had sufficient power and few allowed for confounders. We found that research to date implicates associations with prenatal drinking ≥4 drinks of alcohol per day; diabetes; taking antidepressant drugs; being deficient in iodine or iron; dietary fish; and postnatal depression. The child appearing to be most at risk was born of low birth weight (but not due to preterm delivery) or with neonatal problems.

Parental, prenatal, and neonatal associations with ball skills at age 8 using an exposome approach

There is little consistency in the literature concerning factors that influence motor coordination in children. A hypothesis-free "exposome" approach was used with 7359 children using longitudinal information covering 3 generations in regard to throwing a ball accurately at age 7 years. The analyses showed an independent robust negative association with mother's unhappiness in her midchildhood (6-11 years). No such association was present for study fathers. The offspring of parents who described themselves as having poor eyesight had poorer ability. This hypothesis-free approach has identified a strong negative association with an unhappy childhood. Future studies of this cohort will be used to determine whether the mechanism is manifest through differing parenting skills, or a biological mechanism reflecting epigenetic effects.