Research That Has Been Conducted with Boys Who Have a Gene

Research that has been conducted with boys who have a gene that produces lower levels of MAO-A (which has been associated with aggression) found that these boys have

A) higher levels of aggression as adults, regardless of the circumstances in which they are raised.
B) higher levels of aggression as adults, but only if they had experienced abuse during their childhood.
C) typical levels of aggression as adults, but higher levels of anxiety about their aggressiveness.
D) lower levels of aggression, regardless of the circumstances in which they were raised.