Yeah I think both of that are the factor for someone become Gay, but I personally categorize them in two type, one because love, simply they unfortunately fall in love with someone that was in the same gender, due to reasons, and another because lust, which I believe more due to genetic defect that make them have sexual fetish or preference with same gender.
I have to wonder how many people posting to this thread are gay themselves, or have ever really talked to someone who is.
I have never known a gay person to say it was something they chose; they all describe the awakening of their sexuality the same way straight people do. Is being *straight* a choice? I don't remember choosing to be straight, but I am. Why assume being gay is any different?