They are getting close..
"Gayness may not be in our genes, but in the molecules that regulate them. New research suggests that epigenetic factors -- chemical "switches" attached to genes that turn them on or off -- are a more plausible heritable mechanism behind homosexuality than DNA itself."
http://www.popsci.com/science/article/2012-12/being-born-gay-isnt-your-genes-its-them
These epigenetic studies have been debunked, and have to date not shown anything - and have been exposed for being extremely flawed.
http://www.theatlantic.com/science/archive/2015/10/no-scientists-have-not-found-the-gay-gene/410059/