Background: A functional polymorphism in the promoter region of the monoamine oxidizing gene "monoamine oxidase A" ("MAOA") has been associated with behavioral sensitivity to adverse environmental conditions in multiple studies (e.g., Caspi et al. 2002; Kim-Cohen et al., 2006). The present study investigates the effects of…

Background: Variability in behaviour displayed by children with fragile X syndrome (FXS) may be partially attributable to environmental factors such as maternal responsivity. The purpose of this study was to explore variables associated with maternal behaviour during a task designed to elicit frustration in their children with FXS. Methods:…

In the current study, we examined parent gender differences in feelings (negativity and positivity) and perceptions of child behavioural and emotional problems in adoptive and biological parent-child dyads. In a sample of 85 families, we used a novel within-family adoption design in which one child was adopted and one child was a biological child…

Objective: To examine the underlying mechanisms of adults' intended caregiving responses to cry sounds in a behavioral genetic design and to investigate the role of cry pitch and perceived urgency in sensitive and harsh caregiving responses. Methods: The sample consisted of 184 adult twin pairs (18-69 years), including males and females, parents…

Background: The 22q11.2 deletion syndrome (22qDS) confers high risk for intellectual disability and neuropsychological/academic impairment, although a minority of patients show average intelligence. Intellectual heterogeneity and the high prevalence of psychiatric diagnoses in earlier studies may have obscured the prototypical neuropsychological…

It is often assumed that differences in teacher characteristics are a major source of variability in children's educational achievements. We examine this assumption for early literacy achievement by calculating the correlations between pairs of twin children who either shared or did not share a teacher in kindergarten, Grade 1, and Grade 2.…

This study is concerned with ways in which children with Williams syndrome (WS), a rare neurodevelopmental disorder arising from a hemizygous deletion in chromosome band 7q11.23 including the gene for elastin (ELN) and approximately 20 surrounding genes, are affected by social mores of vastly differing cultures: the United States and Japan. WS…

We investigated the role of the ventromedial prefrontal cortex (vmPFC) in extinction of conditioned taste aversion (CTA) by microinfusing a protein synthesis inhibitor or N-methyl-d-asparate (NMDA) receptors antagonist into the vmPFC immediately following a non-reinforced extinction session. We found that the protein synthesis blocker anisomycin,…

A previous finding from our group indicated that teacher-rated antisocial behaviour (AB) among 7-year-olds is particularly heritable in the presence of callous-unemotional (CU) traits. Using a sample of 1865 same-sex twin pairs, we employed DeFries-Fulker extremes analysis to investigate whether teacher-rated AB with/without CU traits also shows…

Affiliation with substance using peers is one of the strongest predictors of adolescent alcohol use. This association is typically interpreted causally: peers who drink incite their friends to drink. This association may be complicated by uncontrolled genetic and environmental confounds because teens with familial predispositions for adolescent…

Background: Comorbidity amongst anxiety disorders is very common in children as in adults and leads to considerable distress and impairment, yet is poorly understood. Multivariate genetic analyses can shed light on the origins of this comorbidity by revealing whether genetic or environmental risks for one disorder also influence another. We…

According to the National Organization for Rare Disorders (NORD), a rare or "orphan" disease affects fewer than 200,000 people in the United States. There are more than 6,000 rare disorders that, taken together, affect approximately 25 million Americans. "Exceptional Parent" ("EP") recognizes that when a disorder affects a child or adult, it…

Understanding the development of religiousness is an important endeavor because religiousness has been shown to be related to positive outcomes. The current study examined mean-level, rank-order, and individual-level change in females' religiousness during emerging adulthood. Genetic and environmental influences on religiousness and its change and…

In this article, the authors describe an interconnected set of relatively simple laboratory experiments in which students determine the RNA content of yeast cells and use agarose gel electrophoresis to separate and analyze the major species of cellular RNA. This set of experiments focuses on RNAs from the yeast "Saccharomyces cerevisiae", a…

Scientists are not sure of how corn was created. There were two competing genetic theories about how corn came to be. One theory maintains that corn had been teased out of a wheatlike grass called teosinte (genus Zea), and the other contends that one now-extinct ancestor of corn had crossed with another grass, "Tripsacum," several millennia ago.…