The Boston Globe:
AGGRESSIVE PEOPLE SHOULD also be strong; otherwise, they might pick a fight they can’t win. But this raises an interesting chicken/egg problem: Do aggressive people start out strong and learn later that they can act aggressive, or do they start out aggressive and then grow strong? Research on twins in Minnesota revealed that boys with greater self- and teacher-reported aggressive-antisocial tendencies at age 11 were not consistently stronger—as measured by handgrip strength—than other boys. However, by age 17, they were significantly stronger. In other words, guys who start out acting tough later grow the strength to back it up.
Read the whole story: The Boston Globe