The purpose of the current study was to determine the genetic and environmental contributions to the development of prosocial behavior in children using a population of 356 twins at 8 years of age. The study also aimed to examine whether qualities of parenting (specifically authoritarian and authoritative parenting styles) were phenotypic predictors of prosocial behavior. Both parent-reports and objective ratings of global prosocial behavior were used. Results supported prosocial behavior as a genetically-influenced trait with heritability estimates of 44% and 68% for parent reported and observed prosocial behavior, respectively. Data also suggested prosocial behavior as an environmentally-influenced trait. As hypothesized, authoritative parenting was moderately correlated with parent-reported prosocial behavior and authoritarian parenting was found to be low-to-moderately negatively correlated with parent-reported prosocial behavior. Multi-variable regressions demonstrated that authoritative parenting was significantly predictive of increased parent-reported prosocial behavior but authoritarian parenting was not predictive of decreased parent reported prosocial behavior. However, observed prosocial behaviors were largely independent of both authoritative and authoritarian styles of parenting.

Approximately 95% of Americans have at least one sibling (Weaver, Coleman, & Ganong, 2003), making it more likely that children grow up with a sibling than with a father (Lyon, 2009). It is therefore somewhat surprising to learn that sibling relationships have not been a central focus of psychological research, especially considering the fact that parent-child and peer relationships have been studied so extensively. There is no doubt that parents and peers have profound effects on children's emotional, psychological and social wellbeing, but siblings have important effects as well. By middle childhood, children spend more time with their siblings than they do with their parents (Pike, Coldwell, & Dunn, 2005). The sibling relationship is one of the longest and most lasting relationships that we as humans have. Approximately 78% of Americans over the age of sixty still have contact with at least one sibling (Cicirelli, 1995). Unlike parents, siblings are often in our lives until the end of our lifespan and, unlike friends, we do not choose them. They act as teachers, friends, and critics, just to name a few, and they are often a sounding board off of which we can test our ideas and behaviors. The focus of the current study is on the twin sibling relationship quality in middle childhood and in adolescence and its implications for individual adjustment, specifically in the realm of prosocial and aggressive behaviors. I evaluated twin sibling cooperation and conflict at both age 7-8 years and age 12-14 years and then examined prosocial and aggressive tendencies concurrently and longitudinally to study the strength of the association between the two. This study also aimed to better understand the extent to which prosocial behavior and aggression are influenced by genetic and environmental factors.

The relationship between parent and child is one that has been studied intensively for years. Much of the previous research in this field has quantified the parent-child relationship through self-report measures, with a subsample coding behavior from videotape and averaging individual scores across the entire parent-child interaction. Using a dynamic systems approach, we attempted to gain a deeper understanding of the parent-child relationship by quantifying the relationship in terms of dyadic patterns using the software Gridware. We then used these dyadic patterns to predict internalizing and externalizing behaviors in eight-year-old twin children. Dyadic relationship patterns predicted externalizing behaviors such as aggression and conduct disorder (i.e., frequency and stability within negative attractor states, and infrequency and low stability in positive attractor states), but not internalizing behaviors. Findings provide a method for capturing variance in parent-child interactions that is important for children's externalizing behaviors. Future studies should utilize these patterns in understanding risk and resilience family processes for children's mental health and well being.

We examined the relations between maternal depression, discipline practices, and toddler mental health outcomes, specifically competence and total problem behavior. Ethnicity was considered as a moderator in all analyses. For the first time, ethnicity was considered as a moderator of the heritability of toddler competence and total problem behavior. The data came from the Arizona Twin Project. A subsample containing only Caucasian (66%) and Hispanic (34%; 87% of Mexican descent) participants was used. Primary caregivers (>95% mothers) reported on levels of maternal depression, discipline practices, and their twins' competency and problem behaviors. It was hypothesized that maternal depression would be associated with less competency and more problem behaviors in toddlers; inductive discipline practices would be associated with higher competency and fewer problem behaviors; and punitive discipline practices would be associated with lower competency and more problem behaviors. Ethnicity was predicted to moderate only the relation between discipline practices and toddler mental health. Consistent with predictions, maternal depression predicted less competency and more problem behaviors, and inductive discipline predicted higher competency and fewer problem behaviors, while punitive discipline predicted lower competency and more problem behaviors. Ethnicity moderated the relation between maternal depression at 12 months and total problem behaviors. The heritability of competence and total problem behavior varied across the Caucasian and Hispanic samples.

The relations between prenatal risk factors and postnatal risk and protective factors and infant outcomes were examined. Mothers, primarily of low-income background and Latina ethnicity, were interviewed within 24 hours of giving birth, and then again when their infants were five and nine months of age. The relations between prenatal stress, postnatal environment, and infant maturity and temperament were analyzedusing a multiple regression model. We controlled for the covariates: mother's education level and infant's birth weight. Maternal prenatal risk factors predicted lower infant Regulation and lower Developmental Maturity at nine months. Maternal postnatal risks did not predict infant outcomes, but maternal expectations for their child provided a significant association for three of the four infant outcomes: Regulation, Surgency, and Infant Developmental Maturity. The results underscore the importance of prenatal stress holding its significance with the addition of postnatal measures. Future studies would need to explore deeper into a multitude of postnatal factors, in order to accurately portray associations between maternal prenatal stress and infant health.

Built upon Control Value Theory, this dissertation consists of two studies that examine university students’ future-oriented motivation, socio-emotional regulation, and diurnal cortisol patterns in understanding students’ well-being in the academic-context. Study 1 examined the roles that Learning-related Hopelessness and Future Time Perspective Connectedness play in predicting students’ diurnal cortisol patterns, diurnal cortisol slope (DS) and cortisol awakening response (CAR). Self-reported surveys were collected (N = 60), and diurnal cortisol samples were provided over two waves, the week before a mid-term examination (n = 46), and the week during students’ mid-term (n = 40). Using multi-nomial logistic regression, results showed that Learning-related Hopelessness was not predictive of diurnal cortisol pattern change after adjusting for key covariates; and that Future Time Perspective Connectedness predicted higher likelihood for students to have low CAR across both waves of data collection. Study 2 examined students’ future-oriented motivation (Future Time Perspective Value) and socio-emotional regulation (Effortful Control and Social Support) in predicting diurnal cortisol patterns over the course of a semester. Self-reported surveys were collected (N = 67), and diurnal cortisol samples were provided over three waves of data collection, at the beginning of the semester (n = 63), during a stressful academic period (n = 47), and during a relaxation phase near the end of the semester (n = 43). Results from RM ANCOVA showed that Non-academic Social Support was negatively associated with CAR at the beginning of the semester. Multi-nomial logistics regression results indicated that Future Time Perspective Value and Academic Social Support jointly predicted CAR pattern change. Specifically, the interaction term marginally predicted a higher likelihood of students switching from having high CAR at the beginning or stressful times in the semester to having low CAR at the end the semester, compared to those who had low CAR over all three waves. The two studies have major limits in sample size, which restricted the full inclusion of all hypothesized covariates in statistical models, and compromised interpretability of the data. However, the methodology and theoretical implications are unique, providing contributions to educational research, specifically with regard to post-secondary students’ academic experience and well-being.

This study examined whether social support available to parents moderated the heritability of parent-reported social approach at 12 months (N = 286 twin pairs, 52.00% female) and social competence at 30 months (N = 259 twin pairs, 53.30% female). Genetic and environmental covariance across age is also reported. Social support consistently moderated genetic influences on children’s social approach and competence, such that heritability was highest when parents reported low social support. Shared environment was not moderated by social support and explained continuity across age. Findings provide further evidence that genetic and environmental influences on development vary across context. When parents are supported, environmental influences on children’s social competence are larger, perhaps because support helps parents provide a broadly promotive environment.

The current study utilized data from two longitudinal samples to test mechanisms in the relation between a polygenic risk score indexing serotonin functioning and alcohol use in adolescence. Specifically, this study tested whether individuals with lower levels of serotonin functioning as indexed by a polygenic risk score were vulnerable to poorer self-regulation, and whether poorer self-regulation subsequently predicted the divergent outcomes of depressive symptoms and aggressive/antisocial behaviors. This study then examined whether depressive symptoms and aggressive/antisocial behaviors conferred risk for later alcohol use in adolescence, and whether polygenic risk and effortful control had direct effects on alcohol use that were not mediated through problem behaviors. Finally, the study examined the potential moderating role of gender in these pathways to alcohol use.

Structural equation modeling was used to test hypotheses. Results from an independent genome-wide association study of 5-hydroxyindoleacetic acid in the cerebrospinal fluid were used to create serotonin (5-HT) polygenic risk scores, wherein higher scores reflected lower levels of 5-HT functioning. Data from three time points were drawn from each sample, and all paths were prospective. Findings suggested that 5-HT polygenic risk did not predict self-regulatory constructs. However, 5-HT polygenic risk did predict the divergent outcomes of depression and aggression/antisociality, such that higher levels of 5-HT polygenic risk predicted greater levels of depression and aggression/antisociality. Results most clearly supported adolescents’ aggression/antisociality as a mechanism in the relation between 5-HT polygenic risk and later alcohol use. Deficits in self-regulation also predicted depression and aggression/antisociality, and indirectly predicted alcohol use through aggression/antisociality. These pathways to alcohol use might be the most salient for boys with low levels of socioeconomic status.

Results are novel contributions to the literature. The previously observed association between serotonin functioning and alcohol use might be due, in part, to the fact that individuals with lower levels of serotonin functioning are predisposed towards developing earlier aggression/antisociality. Results did not support the hypothesis that serotonin functioning predisposes individuals to deficits in self-regulatory abilities. Findings extend previous research by suggesting that serotonin functioning and self-regulation might be transdiagnostic risk factors for many types of psychopathology.

The following study was developed to investigate the development of writing skills in second and third grade students. The recent emphasis on writing, specifically writing in multiple genres, made in the Common Core State Standards (CCSS, 2010) has increased the need to further understand how students write. The NAEP (2002) reports that approximately 77% of fourth grade students have only a general grasp of writing. Despite this poor performance, the Common Core State Standards (CCSS, 2010) have increased the expectations for student writing. The goal of this proposed dissertation, using an holistic literacy perspective, is to shed light on differences in how students write in informative and opinion genres, which skills predict writing outcomes, the extent to which reciprocal effects between writing and literacy are present, and what type of student profiles exist within the classroom. It was found that students received lower scores on opinion writing compared to their informative compositions. It was also found that better reading comprehension was associated with better writing performance in both genres. High vocabulary ability predicted higher opinion essay scores and better performance on a behavioral regulation task predicted better informative essay outcomes. Reciprocal effects between writing outcomes and literacy skill were found, with higher opinion writing scores predicted higher vocabulary outcomes. Finally, students appeared to fall into four latent profiles: high achievers, average achievers, struggling students, and a group of students who have average literacy skill but scored extremely poorly on the opinion essay task.

The purpose of this study was to examine whether maternal personality (i.e., Agreeableness and Conscientiousness) predicted maternal positive parenting (i.e., warmth/sensitivity and structure), and whether maternal parenting predicted children's regulation and sympathy and/or prosocial behavior. Additionally, the mediated effect of maternal warmth/sensitivity on the relation between maternal Agreeableness and children's regulation and the mediated effect of maternal structure on the relation between maternal Agreeableness and children's observed sympathy/prosocial behavior were investigated. Maternal personality was measured when children (N = 256 at Time 1) were 18 months old; maternal parenting was assessed when children were 18, 30, and 42 months old; children's regulation and sympathy/prosocial behavior (observed and reported) were assessed when children were 30, 42, and 54 months old. Mothers reported on their personality; maternal warmth/sensitivity was observed; maternal structure was observed and mothers also reported on their use of reasoning; mothers and caregivers rated children's regulation (i.e., effortful control [EC]) and regulation was also observed; mothers and fathers rated children's prosocial behavior; sympathy and prosocial behavior were also observed. In a path analysis, Conscientiousness did not significantly predict maternal warmth/sensitivity or structure at 30 months, whereas Agreeableness marginally predicted maternal warmth/sensitivity at 30 months and significantly predicted maternal structure at 30 months. Maternal warmth/sensitivity at 18 months significantly predicted 30-month EC, and 30-month maternal warmth/sensitivity significantly predicted 42-month EC. Maternal structure at 30 months significantly predicted 42-month observed sympathy/prosocial behavior. Maternal warmth/sensitivity at 42 months significantly predicted 54-month observed sympathy/prosocial behavior and marginally predicted 54-month reported prosocial behavior. Maternal structure and EC did not significantly predict reported prosocial behavior across any time point. EC did not significantly predict observed sympathy/prosocial behavior across any time point and maternal warmth/sensitivity at 18 and 30 months did not predict observed or reported sympathy/prosocial behavior at 30 or 42 months, respectively. Maternal Agreeableness directly predicted 30-month reported prosocial behavior and additional paths suggested possible bidirectional relations between maternal warmth/sensitivity and structure. Mediation analyses were pursued for two indirect relations; however, neither mediated effect was significant. Additional results are presented, and findings (as well as lack thereof) are discussed in terms of extant literature.