Gene-environment correlations: a review of the evidence and implications for prevention of mental illness

Family studies have demonstrated genetic influences on environmental exposure: the phenomenon of gene-environment correlation (rGE). A few molecular genetic studies have confirmed the results, but the identification of rGE in studies that measure genes and environments faces several challenges. Using examples from studies in psychology and psychiatry, we integrate the behavioral and molecular genetic literatures on rGE, describe challenges in identifying rGE and discuss the implications of molecular genetic findings of rGE for future research on gene-environment interplay and for attempts to prevent disease by reducing environmental risk exposure. Genes affect environments indirectly, via behavior and personality characteristics. Associations between individual genetic variants and behaviors are typically small in magnitude, and downstream effects on environmental risk are further attenuated by behavioral mediation. Genotype-environment associations are most likely to be detected when the environment is behaviorally modifiable and highly specified and a plausible mechanism links gene and behavior. rGEs play an important causal role in psychiatric illness. Although research efforts should concentrate on elucidating the genetic underpinnings of behavior rather than the environment itself, the identification of rGE may suggest targets for environmental intervention even in highly heritable disease. Prevention efforts must address the possibility of confounding between rGE and gene-environment interaction (G x E).

Predicting early fatherhood and whether young fathers live with their children: prospective findings and policy reconsiderations

This prospective study of a birth cohort addressed three questions. Which individual and family-of-origin characteristics predict the age at which young men make the transition to fatherhood? Do these same characteristics predict how long young men live with their child? Are individual differences in the amount of time fathers spend living with their child associated with the father's psychosocial characteristics in young adulthood? In this unique study, it was found that by age 26, 19% of the 499 study men had become fathers. Individual and family-of-origin characteristics were assessed from birth until age 15 and contemporaneous characteristics were assessed at age 26. Young men who experienced a stressful rearing environment and a history of conduct problems were more likely to become fathers at an early age and to spend less time living with their child. Of those who experienced none of the risk factors, fewer than 10% had become fathers by age 26 compared to more than 60% of those who experienced five risk factors. Fathers who lived apart from their child reported the most social and psychological difficulties in young adulthood. These findings point to individual and family-of-origin characteristics that might be targeted in order to delay fatherhood and increase levels of paternal involvement. However, given their troubled life histories and poor social-psychological adjustment in young adulthood, some absent fathers might have difficulties providing positive parenting and partnering unless policy initiatives to promote intact families also support young fathers.

Predicting early fatherhood and whether young fathers live with their children: prospective findings and policy reconsiderations

This prospective study of a birth cohort addressed three questions. Which individual and family-of-origin characteristics predict the age at which young men make the transition to fatherhood? Do these same characteristics predict how long young men live with their child? Are individual differences in the amount of time fathers spend living with their child associated with the father's psychosocial characteristics in young adulthood? In this unique study, it was found that by age 26, 19% of the 499 study men had become fathers. Individual and family-of-origin characteristics were assessed from birth until age 15 and contemporaneous characteristics were assessed at age 26. Young men who experienced a stressful rearing environment and a history of conduct problems were more likely to become fathers at an early age and to spend less time living with their child. Of those who experienced none of the risk factors, fewer than 10% had become fathers by age 26 compared to more than 60% of those who experienced five risk factors. Fathers who lived apart from their child reported the most social and psychological difficulties in young adulthood. These findings point to individual and family-of-origin characteristics that might be targeted in order to delay fatherhood and increase levels of paternal involvement. However, given their troubled life histories and poor social-psychological adjustment in young adulthood, some absent fathers might have difficulties providing positive parenting and partnering unless policy initiatives to promote intact families also support young fathers.