So we choose whether to be left or right handed?
Tall or short?Artistic or practical?Violent or gentle?Christian or atheist?Healthy or sickly? What makes them attracted to the opposite sex or not? Is that a choice?
The problem that you have here is that you are arguing from a position of belief. Homosexuality
must be a sinful, lifestyle choice because god condemns it in the Bible. It is not a position based on evidence, just assertion.
Unfortunately (for your position), research has found that there
are biological and genetic factors that affect our sexuality, as well as environmental. And the research has not stopped. You have basically staked all your theological chips on science never proving a link between biology and sexuality.
Good luck with that!
http://www.theguardian.com/science/blog/2015/jul/24/gay-genes-science-is-on-the-right-track-were-born-this-way-lets-deal-with-it