The idea of a gay gene has been long debated and sought after among geneticists. After years of persecution and discrimination, some members of the LGBT community support such a search, in the hopes of scrapping the argument that their way of life is unnatural. Others vehemently oppose it, however, since they claim that it will only open up a worse form of discrimination. They believe that those who oppose same-sex relationships may be able to alter their children's genetic makeup if it is revealed they have a homosexual predisposition. In a recent international study, however, a single genetic marker for homosexuality now seems rather unlikely. What seems more likely is partial polygenic predisposition in conjunction with environmental factors. According to the study, only about 25% of human sexual behavior can be explained by genetics, with the rest being explained by environment and local culture. As with most behavioral patterns, a sole genetic linkage is often not the cause of these phenotypes. While this polygenic expression of phenotype allows for more diversity, it of course results in a much more difficult time deciphering the genetic origins of human and animal behavior.
Comments
Excess
The writing is solid overall and the paragraph flows but there is some excessive wording. For example "The idea of a gay gene..." could be shortened to "The gay gene...", as this conveys the same information in the context of the paragraph.
More Direct
"After years of persecution and discrimination, some members of the LGBT community support such a search, in the hopes of scrapping the argument that their way of life is unnatural."
I had to read this sentence a few times because at first I thought you were saying that LGBT community was claiming their way of life was unnatural. I think I read it that way because the comma after the word search is not needed. You could omit "such a search" and just say that LGBT communities support the search for a gay gene with the hope that they can scrap the arguement of their lifestyle being unnatural.
Story-telling wording
Although you get your point across, some of the wording seems a little sing-songish and out of plae. The use of "however" multiple times makes it seem like you're telling a story instead of relaying information.