Choose two theories for why people differ in sexual orientation. Explain how they account for variance in sexual orientation, what evidence supports each, and whether each approach most reflects a biological, evolutionary, or integrative perspective.

Question

What will be an ideal response?

Answer 1

Responses may include any two theoretical approaches described in the text. A sample answer may proceed as follows: The fraternal birth order effect represents a biological approach. Its proponents argue that male fetuses emit an antigen that evokes a maternal immune response that grows stronger with each subsequent male fetus. At a certain point, the mother produces enough antibodies to prevent the fetal brain from developing in the male-typical fashion, resulting in male homosexuality. This account is supported by the positive correlation between number of older brothers a male has and his own likelihood of identifying as gay. This effect is also exclusive to men, and cannot be explained by environmental factors as revealed by adoption studies. One evolutionary account of sexual orientation, the alliance formation hypothesis, argues that same-sex sexual activity promotes beneficial friendship bonds between unrelated primate pairs. If such behavior increases survival rates, then it should get transmitted genetically from one generation to the next. For example, researchers have observed that friend pairs who bond with the same-sex sexual activity are more likely to display reciprocal altruism, however this hypothesis is derived purely from studies of nonhumans.