Gay supporters sometimes tell stories about people who were once married normally, divorced to be with a gay partner. The belief is that they were “really” homosexual, and were only “acting” heterosexual.
If that is true, then it is also possible that someone who is “acting” homosexual is “really” heterosexual.
How would you know the difference?
People are born male/female based on XY chromosones. That’s the only sexual gene. So you can say that people are born with sexuality, but you cannot say they are born with lifestyle choices. No such lifestyle gene has been found.