I never said a preference is a choice.
But you DID say that I "prefer" chocolate, and you DID say that "preference, by definition, assumes there IS a choice". So clearly, you are saying that I have a choice. But then you say that, "I don't really think that gay people choose their preference". Which leads me to believe that you don't feel gay people have a choice, and that this is therefore different than my affinity for chocolate. And that simply isn't the case. Regardless of what definitions you use, and whether you call it a "preference", a "choice", a "genetic mutation", or whatever, my point remains--I have as much control over and ability to override my affinity for chocolate as a homosexual has over their affinity for people of the same gender. We can both pretend it doesn't exist. We can both choose to not act on it for significant periods, perhaps even for a lifetime. But in the long run, regardless of all that, I am a chocoholic, and the homosexual is a a homosexual--regardless of how you choose to define "prefer", "choice", or anything else.
If you want to call my affinity for chocolate a "preference", that's fine--then by that definition, homosexuality is a "preference".
If you want to call my affinity for chocolate a "choice", that's fine--then by that definition, homosexuality is a "choice".
If you want to say that my affinity for chocolate is neither a "preference" or a "choice", and that it's something in my genetics, that's fine--then by that definition, homosexuality is neither a "preference" or a "choice".
In the long run, it doesn't matter what terminology you use, as long as you can acknowledge that, when it comes to things we "choose" or "prefer" or "are", these two characteristics belong in the same category.