Is there a so-called “gay gene” that predisposes a male towards homosexuality? This is one of the most controversial topics in modern genetics, with extensive debate both pro and con. Three of the many past research efforts constitute the major underpinnings of this topic. In 1991, Simon LeVay reported that the INAH3 hypothalamus area (supposedly related to male-type sexual behavior) of homosexual autopsied brains was smaller in size than that of heterosexual men, and was in fact closer to the size and structure observed in female brains. In 1993, Dean Hamner published data along with his associates from the U.S. National Cancer Institute suggesting that the Xq28 section of the human X chromosome (found only in males) contained a gene predisposing males to homosexuality. Hamner’s work was based on findings from 33 out of 40 pairs of homosexual brothers. This work was assailed throughout the mid-1990s, culminating in 1999 with counterclaims by George Rice and George Ebers presenting results that “do not support an X-linked gene underlying male homosexuality” based on a study of 52 pairs of Canadian gay brothers. The question remains open, with a still active US Government research program known as 92-C-0078 still seeking thousands of gay siblings as research subjects.