Final answer:
Genetic and environmental factors influence sexual orientation in men.
Step-by-step explanation:
The fact that the identical twin of a gay man has a 50% chance of being gay suggests that genetic factors play a large role in influencing sexual orientation in men. On the other hand, the fraternal twin of a gay man only has a 15% chance of being gay, indicating that genetic factors play a minor role. This implies that environmental factors also contribute to determining sexual orientation in men.
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