http://www.google.com/search?q=homosexual+and+brain+structure
http://www.versiondaily.com/the-male-homosexual-brain-structural-and-functional-difference/
To a certain extent, homosexuals are biologically different from heterosexuals as evident from the structural or anatomical and functional difference between their brains. This fact further establishes the biological underpinning of sexual orientation and homosexuality.
Acclaimed Dutch neurologist **** F. Swaab mentioned in his review of literatures that sexual differentiation of the human brain occurs during the fetal and neonatal development that subsequently programs sexual orientation and gender identity. This biological development process involving sexual differentiation is accompanied by many structural and functional brain differences among heterosexual, homosexual, and even bisexual groups.
http://www.bu.edu/thenerve/archives/spring-2010/reviews-spring-2010/homosexuality/
In a key article, Simon LeVay presented the difference in hypothalamic structure between heterosexual and homosexual men3. Cited by a majority of articles in the field, LeVay?s hypothesis and study was expository and led to extensive additional research. LeVay argued that the hypothalamus held the the key to sexual orientation. He cited that, in male monkeys, lesions in this region impair heterosexual behavior without eliminating sexual drive3.
https://www.newscientist.com/article/dn14146-gay-brains-structured-like-those-of-the-opposite-sex/
Brain scans have provided the most compelling evidence yet that being gay or straight is a biologically fixed trait.
The scans reveal that in gay people, key structures of the brain governing emotion, mood, anxiety and aggressiveness resemble those in straight people of the opposite sex.
https://www.outfrontmagazine.com/news/the-gay-brain-what-makes-us-lgbt/
https://www.scientificamerican.com/article/study-says-brains-of-gay/
http://news.bbc.co.uk/2/hi/health/7456588.stm