Research

My research involves the study of heredity, environment and individual differences in human behavior. This includes various human traits, including cognitive abilities, personality, gender roles, and positive and negative affect. My team is particularly interested in the roots of aggression and externalizing psychopathology across the lifespan. Studies of twins, adoptees and other family member are ways of understanding how genes and environment affect our behavior.  We study community samples who represent the full range of behavior, both normal and abnormal, to understand how experiences and genetic predispositions together can lead to different mental health outcomes.

I direct the USC Twin Project, which includes a large registry of twins in Los Angeles and the surrounding community. Since 2000 my team has been running a comprehensive study of social and moral development from childhood to young adulthood through support from the National Institutes of Mental Health (NIMH).  We also investigate the role of air pollution and greenspace on cognitive and social outcomes with support from the National Institute of Environmental Health Sciences.