Larry, if you have daughters, you probably at least at some level feel certain attraction to them (this is entirely normal and one of the historical reasons that you and I are talking on here, but since you disliked math and geography, offering you history of the study of psychology now would be way too imposing if not outright rude on my part ) and try to suppress those feelings because of the taboos associated with them. For you to look at a 20 year old as a potential date would challenge and threaten the suppression that you have built up in your mind. At least this is usually what happens when fathers or grandfathers talk about 20 year old women as children - they are trying to suppress uncomfortable feelings. So has been my experience, and I can tell you that this kind of thing can be very damaging to the daughters or granddaughters of such over-protective fathers or grandfathers. If this rings true, I can elaborate, but if it does not ring true, then please accept my apologies for making unfounded assumptions about you and your relationships with your daughters.