One genetic study that has many people concerned is the search for the "gay gene." The discovery of this gene began in the 1990s and it is still under debate whether the gene exists and whether it really influences sexual orientation. Several studies have been completed examining sexual orientation through behavioral and molecular genetics. Most of these studies, however, have not been replicated and raise ethical questions. Simon LeVay, a neuroscientist who studied brain function and sexual orientation (Wikipedia contributors, 2014), published an article, “A Difference in Hypothalamic Structure Between Heterosexual and Homosexual Men,” in 1991, which suggested biological reasoning to sexual orientation. LeVay believed that the hypothalamus, which is a region of the brain involved in sexual behaviors, was a biological substrate for sexual orientation (1991). LeVay suggested that the anterior hypothalamus “participates in the regulation of typical male sexual behavior” (1991). LeVay's research has indicated that there is a difference in volume of the third interstitial nucleus of the anterior hypothalamus (INAH 3) between women, homosexual men, and heterosexual men. INAH 3 has been found to have twice the volume among heterosexual men compared to that of women and homosexual men (LeVay, 1991). LeVay concluded that INAH 3 is dimorphic with sexual orientation, meaning that INAH 3 is physically different when comparing sexual orientation between groups of individuals. In 1991, a behavioral geneticist, Michael Bailey, proposed that genes might contribute to homosexuality in males (Wickelgren, 1999). Bailey found that 52% of identical male twins were homosexual compared to 22% of fraternal male twins (Wickelgren, 19...... middle of paper ...... o. 5119 (1993): 291-92 .JSTOR. Web. 01 March 2014. .Rice, William R. and Sergey Gavrilets. "Genetic Models of Homosexuality: Generating Testable Predictions: Biological Sciences 273.1605 (2006): 3031-038 Web. .Schüklenk, Udo, Edward Stein, Jacinta Kerin, and William Byne. “The ethics of genetic research on sexual orientation.” Wickelgren, Ingrid. “Discovery of the 'gay gene'.” Vol 284, No. 5414: 571 . JSTOR 01 March 2014. "Simon LeVay." Wikipedia, the free encyclopedia. Wikipedia, the free encyclopedia, 8 January 2014. Web. 1 March. 2014.