Twin Studies Conducted to Examine the Genetic Contribution to Prosocial

Twin studies conducted to examine the genetic contribution to prosocial behaviour have found that

A) fraternal twins and identical twins are equally similar to each other in levels of prosocial behaviour, and their similarity decreases with age.
B) fraternal twins and identical twins are equally similar to each other in levels of prosocial behaviour, and their similarity increases with age.
C) identical twins are more similar to each other in levels of prosocial behaviour than are fraternal twins, and their similarity decreases with age.
D) identical twins are more similar to each other in levels of prosocial behaviour than are fraternal twins, and their similarity increases with age.