Concerning the Minnesota Reunited Twin Studies, Which of the Following

Concerning the Minnesota reunited twin studies, which of the following aspects of their lives is more likely to be due to genetic similarities than to living in the same historical time period?

A) Both twins like banana splits and cheeseburgers.
B) Both twins are Democrats.
C) Both twins have a nervous tic, like nail biting.
D) Both twins joined the National Guard.