Well they were certain it was all genetic, but years and years of research did not bear that out. So now they simply declare it unchangeable, which is the next best thing. The left is using 'science' to advance their whacky politics in numerous areas and it is fooling more and more people.
Unfortunately for them, their worldview has been demolished:
People Can Change
Is it Really Possible?
Why Change?
Root Causes, Homosexual Consequences