Is homosexuality a genetic problem?

Your question is not one that relates to halacha (=Jewish law) but is rather a medical or biological question. The Torah forbids both male and female homosexuality. The fact that there is a commandment against homosexuality means that even a person with a predisposition (whether genetic or learned or otherwise acquired) to homosexuality can (because of Man's free will) overcome this. The Torah commands him to exert his will so as not to engage in prohibited behavior.