The genetic and environmental etiology of emotion regulation in toddlerhood

Emotion regulation (ER) refers to the processes of the modulation on multiple components of emotion including experiential feelings, behavioral tendencies, physiological reactions, and cognitive processes based on the social context. In spite of a growing body of empirical work on ER, relatively little research has investigated the genetic contributions to individual differences in ER. The first goal of the present study was to address this gap in the literature by investigating the genetic and environmental etiology of individual differences in ER in toddlers. The second goal was to investigate the development of ER in toddlerhood and factors that influence stability and change in ER. The third goal was to explore ER and other related constructs including temperament, cognitive abilities, parent-child relationships, and behavioral problems; and to use behavioral genetic methods to examine genetic and environmental influences on the overlap between ER and associated variables.;The current study utilized a sample of 314 same-sex twin pairs (145 MZ, 169 DZ) who participated in the Boston University Twin Project at age 2 and 3 years. At both ages, the Behavior Rating Scale (BRS) of the Bayley Scales of Infant Development-Second Edition (BSID-II) was used to assess ER. This is the first study providing empirical evidence that individual differences in ER in toddlerhood are influenced by genetic and nonshared environmental effects. Genetic factors account for approximately half of the variance in ER at both ages (53% and 54% at ages 2 and 3, respectively), while the remaining variance is due to nonshared environmental influences. ER is moderately stable from ages 2 to 3 (r=.41). Genetic effects contribute to the stability whereas genetic and nonshared environmental factors explain change in ER across age. Toddlers' ER is significantly associated with their temperamental traits including inhibitory control and activity level; and mental development, working memory, elicited imitation; and parent-child dyadic mutuality (r=.30-.58). Common genetic effects largely explain these associations. Because of the link between ER and psychopathology, knowledge of the factors that influence individual differences in ER and the covariations between ER and other related constructs can inform both prevention and intervention for at-risk children.