Oct 08, · Science Now ; Scientists find DNA differences between gay men and their straight twin brothers. It’s an evolutionary paradox that’s frustratingly difficult for biologists to explain, but researchers may have just found a benefit conferred by homosexual sex that could offer an explanation as to why this behavior has persevered, at least in one species. According to a new study in fruit. History of homosexuality. Jump to navigation Jump to search. This since Tulchin may have discovered the earliest form of same-sex marriage.