Against your eating habits

If homosexuals can't get married because it goes against your religion, you can't have cookies because I'm on a diet.

Quite an apt comparison, I thought, and really goes to highlight how silly the notion actually is. My parents still say that the reason they don’t think it should be acceptable is because it creates ‘chaos’ in society, but I still see homosexual partners bringing up good, morally sound, intelligent children that are in all other respects perfectly normal. What’s the problem here?