If a geneticist selects any arbitrary group of people - for instance, those who enjoy watching football games - and examines them closely enough, he or she may well find a genetic marker common to all of them. But that shared marker need not have anything to do with the fact that they all like football.

The consideration above can best serve as part of an argument against the view that



a. An individual's personality is more likely to be determined by the environment in which he grew up than by his or her genetic makeup.
b. The discovery that alcoholics share a common gene establishes that alcoholism is genetically determined.
c. Certain personality traits are determined neither by environment nor by heredity, but by some unknown third element.
d. Since genetic makeup may determine how one responds to one's environment, scientists cannot assume that heredity plays no role in personality development.
e. Certain personality traits can be reinforced by spending time with others who share that personality trait.