Genetic and environmental influences on change in child activity level during infancy and toddlerhood Laura V. Scaramella, Daniel S. Shaw, Melissa A. Barnett, Ginger Moore, and Rand D. Conger

Characteristics of infant temperament  Conceptualizations of temperament often emphasize: emotional valence (e.g., positive vs. negative), motivation (e.g., approach vs. avoidance), and activity level (Frick, 2006; Nigg, 2006; Rothbart & Bates, 1998; Rothbart & Posner, 2002).

Characteristics of infant temperament  Empirical research often focuses on combinations of characteristics Fearful temperament = high levels of negative emotional valence & avoidance motivation and low activity level Surgency = high levels of positive emotional valence, approach, & activity level

Characteristics of infant temperament  Characteristics of temperament may be differentially influenced by genetic or environmental circumstances  Present investigation considered genetic & environmental influences on child activity level from 9 to 18 months

Infant activity level & adult personality  Infancy temperamental characteristics predict adult personality characteristics (e.g., Caspi, et al., 2003)  High activity level measured during infancy and childhood linked to Less constraint More sensation seeking during adulthood (e.g., Caspi & Silva, 1995; Rothbart & Posner, 2002)

Nature & nurture influences  Continuities in temperament and personality over time suggest genetic influences  Environment has been found to moderate the expression of temperamental characteristics (e.g., Bates, Pettit, Dodge, & Ridge, 1998)  Adoption design – evaluate both genetic and environmental influences

Study hypotheses  Genetic influences: Adopted children’s high activity level will be positively correlated with birth mothers’ surgency  Environmental influences After controlling for birth mother surgency, adopted children’s activity level and adoptive mothers’ parenting will be reciprocally related.

Study design: Early Growth & Development Study  Adoption study, includes: 361 children adopted at birth Adopted parents Birth mothers Subsample of birth fathers  Current study used data collected when Infants were 9 & 18 months Birth mothers were 3 months post-delivery

Sample characteristics  361 yoked family units participated Birth mother, adopted child, adoptive parents  Average age at first participation Birth mothers: 23.8 years Adopted children: 8.8 mo Adoptive mothers: 37.0 years Adoptive fathers: 37.9 years

Sample characteristics, con’t  Most frequently reported annual income Birth mother < $20,000 Adoptive parents > $100,000  Average education level Birth mother = some trade school Adoptive parents = college graduate  Ethnicity Birth mother = 78% white Adoptive parents = 90% white

Measures: Birth mother temperamental surgency  Birth mother temperamental surgency/extroversion Adult Temperament Questionnaire (Derryberry & Rothbart, 1988) Birth mother reports = adopted child ~ 18mo 7 point scale (1 = extremely untrue; 7 = extremely true) Mean of items from 3 subscales (high scores = more surgent)  High intensity pleasure (7 items;  =.62)  Sociability (5 items;  =.72)  Positive affect (5 items;  =.57)

Measures: Adopted child activity level  Adoptive father reports  9 months: Infant Behavior Questionnaire (Rothbart, 1981) 7 point scale (1 = never; 7 = always) (17 items;  =.80)  18 months: Toddler Behavior Questionnaire (Goldsmith, 1996) 7 point scale (1 = never; 7 = always) (20 items;  =.79)

Measures: Adoptive mother parenting  Two parenting measures Parental efficacy (Teti & Gefland, 1981)  how effective mother feels in managing child  Sum of 10 items; 9mo  =.73; 18mo  =.72  4-point scale (1 = not good at all; 4 = very good) Parenting daily hassles (Crnic & Greenberg, 1990)  Frequency of challenging behavior  Sum of 7 items; 9 mo  =.76; 18mo  =.58  4-point scale (1 = rarely; 4 = constantly)

Means & Standard Deviations of Study Constructs MeanSD Birth Mother Surgency AC Activity level (9mo) AC Activity level (18mo) AM Parenting efficacy (9mo) AM Parenting efficacy (18mo) AM Parenting challenges (9mo) AM Parenting challenges (18mo)

Correlations among study constructs Bm surgency Activity: 9m Activity: 18m ** Efficacy: 9m * Efficacy:18m *-.24**.56** Challenges: 9m **-.21**-.22** Challenges: 18m **-.12*-.19**63** Note: + p <.10; * p <.05; ** p <.01.

Results of the hypothesis testing  Structural equation models (AMOS 5.0) were estimated to test each hypothesis  After considering genetic influences on AC activity level, AC activity level and AM parenting efficacy (HYP 1) and perceptions of parenting challenges (HYP2) would be reciprocally related

HYP 1: Parenting Efficacy.16** **.56** -.12* -.10* Fit Indices:  2 (2) = 0.13 RMSEA =.000 CFI = **

HYP 2: Parenting Challenges.16** **.63**.21**.03 Fit Indices:  2 (2) = 0.83 RMSEA =.000 CFI = *

Genetic influences & activity level  Commonalities in Birth Mother surgency and AC activity level seem to exist.  Limited contact between birth mothers and adopted children  Genetic influence seems to be delayed, emerging at 18 mos rather than at 9 mos

Environment & activity level  HYP 1: Parenting efficacy – Evidence for reciprocity More 9mo parenting efficacy predicted declines in activity level Higher 9mo activity level undermined parenting efficacy

Environment & activity level  HYP2: Parenting challenges – No evidence of reciprocity More perceived parenting challenges at 9mo predicted increases in activity level Child activity level had little impact on change in mothers’ perceptions of parenting hassles

Strengths  Independent reports of each factor Genetic factor = Birth mothers Child activity level = Adoptive Fathers Parenting = Adoptive Mothers  Longitudinal design Evaluate the timing of genetic influences Consider environmental influences on change in behavior

Limitations  Unique study design Adoption studies are rare Participants may be unique  No DNA Behavioral measures of surgency and activity level are a proxy for molecular genetic measures Currently collecting DNA from the sample

General Conclusions  Temperamental characteristic of activity level seems to be influenced by Genetic factors – BM temperamental surgency Environmental factors – Parenting efficacy and perceptions of parenting hassles  Children’s activity level seems to impact the environment by undermining parents’ feelings of efficacy.