Which, if any, of the following brothers of a homosexual would be most likely to be homosexual himself?

A) a monozygotic twin brother
B) a dizygotic twin brother
C) an adopted brother
D) All of these would be equally likely to be homosexual, since environment, not genetics, determines sexual orientation.

Monozygotic Twin

Twins that are genetically identical, having developed from a single fertilized egg that split into two.

Dizygotic Twin

Twins that are formed from two separate fertilized eggs, also known as fraternal twins, sharing about 50% of their genetic makeup.

Homosexual

A term used to describe an individual who is attracted emotionally, romantically, or sexually to members of the same sex.