Homosexuality

This week we learned all about forbidden relationships. The Torah explicitly prohibits against homosexuality. This is where I become confused. If the Torah clearly speaks out against homosexuality, then how can people possibly say that they were born that way? It does not seem sensible that G-d, Who prohibits homosexuality, would create a homosexual man. This is why I think this issue is completely due to the person's environment. I think it is not something a person is born with, rather, it is something he develops through time. I think this idea also has to do with free choice. Yes, G-d created man in the image of G-d, but man still has his free choice, and he can use that free choice for the good or bad. For example, a man wasn't born with homosexual thoughts but through time he 'chose' that path. Maybe this portion of Vayikra is trying to remind us to stay on the path of Hashem even if sometimes our nurture/environment is leading us elsewhere. Needless to say this is a very hard challenge!