Some evidence of a biological basis for sexual orientation comes from research that has found that
A) female twins are more likely to become homosexuals than male twins.
B) having an older brother increases the odds of homosexuality in later-born males.
C) a gene associated with sexual preference has been identified by the researchers on the Human Genome Project.
D) children first begin to self-identify as homosexual during the latency period.

Question

Quizplus · Accepted Answer

Research has found that having an older brother increases the odds of homosexuality in later-born males, suggesting a biological basis for sexual orientation. This is known as the fraternal birth order effect.

Answer: C
 While research has identified multiple potential biological factors that may contribute to sexual orientation, a specific gene has not been conclusively identified. However, some studies have suggested that certain variations in genes related to brain development and hormone regulation may play a role in sexual orientation.

Therefore, the best choices are B and C.

Some Evidence of a Biological Basis for Sexual Orientation Comes