Final answer:
LeVay's research indicated that the hypothalamus is significantly larger in heterosexual men than in homosexual men, which has sparked discussions on the biological aspects of sexual orientation.
Step-by-step explanation:
Simon LeVay's controversial research study discovered that an area of the hypothalamus is three times larger in males than in females, and two to three times larger in heterosexual males as compared to homosexual males. The hypothalamus is a forebrain structure that plays an essential role in regulating sexual motivation and behavior, and also serves various homeostatic processes. LeVay's findings contribute to the discussion about biological factors and sexual orientation, though they invite considerable debate and require replication for broader acceptance.