group and the control group with respect to verbal IQ. Minor Physical Anomalies Moffitt writes, "Minor physical anomalies, which are thought to be observable markers for hidden anomalies in neural development, have been found at elevated rates among violent offenders and subjects with antisocial personality traits." Neural development in the fetus may also be affected by maternal drug abuse, poor prenatal nutrition, or prenatal/postnatal exposure to toxic agents. Minor physical anomalies (MPAs) are features such as low-seated ears, furrowed tongue, and adherent ear lobes. Evidence supporting the link between minor physical anomalies and antisocial behavior shows that the link only exists when adverse environmental factors are present. Social Risk Factors In many studies, the individuals displaying antisocial behavior developed in a family exhibiting "deviant behavior," in an "adverse home environment," or in something similar. However most studies do not specify the exact traits that characterize the tested 'deviant' or 'adverse' environment. Many that are cited include abuse, neglect, socioeconomic status, parental antisocial behavior, etc. There is no evidence that social factors, such as these, can induce antisocial behavior without accompanying biological factors. Effect of Biological and Social Risk Factors Together Moffitt projects that initial biological predispositions combined with an adverse rearing environment will initiate the risk of life-course persistent antisocial behavior. She conducted a longitudinal study in New Zealand of boys exhibiting a range of antisocial tendencies. Of the 536 boys, 75 of them had adverse home environments and neuropsychological problems. Those 75 boys scored more than 4 times higher on aggression than the boys with adverse home environments or neuropsychological problems (one of the two). LCP offenders in the Pennsylvania study had higher levels of poverty than the control participants, and they had higher levels of neglect than both the control participants and the AL participants. Additionally, twin studies are often used to isolate effects of nature and nurture. In one such study, the highest criminal activity levels were witnessed in individuals whose foster families exhibited deviant behavior. Genetic and Environmental Interactions The first biological predisposition one thinks of is genetics. Despite Moffitt's original projection that life-course persistent antisocial behavior was more genetically influenced than the adolescent limited variety, a recent study found similar levels of genetic influence on both childhood-onset and adolescent-onset antisocial behavior. Childhood-onset antisocial behavior shares common genetic underpinnings with attention deficit hyperactivity disorder (ADHD) and young adult antisocial behavior, whereas adolescent-onset antisocial behavior does not