An acquaintance of mine has struggled his entire life with his sexual identity. As a boy from a very early age he was molested by his father, a father that was physically and verbally abusive, a father that never showed any love, affection, or caring for him except when it was time to preform sexual favors. During these times his father showed attention, seemed to care, spoke positively, and was kind (Im sure to get what he wanted). He wanted his father to love and care about him just as any of us do. So he started to relate the molestations with love and almost looked forward to these moments as the rest of the time he was largely ignored or abused in other ways. Eventually these times of love (it seemed to him) began to arouse him possibly for abnormal mental reasons (desire for love and affection as he saw it) and he started to enjoy these molestations.
Once he got older and realized the full extent of what was being done to him he was appalled by it. As you can imagine he had many physiological issues as a result. However one link remained, he saw love as a sexual joining of males. He tried for years to have relationships with women but always felt they could not fill the void that was filled by the sex during his childhood. He eventually proclaimed his homosexuality.
Now does this mean he was not born gay? We have no way of knowing one way or the other but it seems plausible that the events if his life may have influenced his sexual outlook perhaps even to the point of complete reversal.