If by that you mean genetically predisposed....well that's not true. Though I'm sure genetics do play a factor sexuality is far more complex than that. That's also sort of a misconception of how genetics work. All sorts of environmental factors can influence the base genetic information and thus provide significantly different results.
Most of the evidence known supports that it is learned behavior. The illogical response by many who have a cultural cowardice and fear of homosexuality is that because it is learned behavior it is immoral and can be unlearned. That's simply not true. Can you unlearn speaking English? Can you unlearn your food and dietary preferences? Can you unlearn your cultural and social patterns of behavior? Can you unlearn to read and write? You see my point....it might be possible to do so but it would be pretty damned difficult. The same is true of learned sexual preferences.