Answer:
Genetic approach.
Explanation:
By the definition from the source, '' behavioral genetics is a type of study of both genetic and environmental influences on certain behavior. By examining influence of the genetics, we can gather more information about how environment affects certain behavior . ''
People said that football is for boys and that's how the information was transferred from generation to generation. Because she knows it's a '' boy's sports '' she immediately comes to conclusion that football is for boys because they're better at it and are more prone to being successful football players and that there is no way that a girl could succeed in it.