My understanding is that people who self identify as gay are a much smaller subset within the group of people who engage in homosexual activities. For example,

My understanding is that people who self identify as gay are a much smaller subset within the group of people who engage in homosexual activities. For example, in my Asian country a large segment of the guys you meet cruising are married men (to women) who identify as completely straight. Perhaps the wife is unwilling to engage in acts you enjoy, and sex with men is low effort high reward. I also knew many guys who preferred sex with men but couldn't fathom a romantic relationship with one, and identified as mostly straight. It's highly likely that most (though not all) of these men were truly gay/bi/pan, but unable to accept it due to social conditioning. I agree that a single encounter probably shouldn't count for the terms of the study.