>>8Yes, and there's your problem. You're basing this on your own experiences.
You don't know if you're the outlier in this situation. For all you know, by 25, most guys/girls have twice as many relationships, with three times as many partners whom they could not pick out of a line up sort of a deal.
But, let's say that every girl who doesn't know who the father is has had eleven partners, in their lifetime.
You then have to account for WHEN those relationships took place. There's a good...two to three week window if I recall, where conception can happen without you realising, if you get me.
So, if a girl has sex with, let's say, three guys in the that period of time, AND she actually knows each of them well enough to say, 'Yeah I can track him down' (being able to pick them out of a line up isn't very handy unless you know stuff like where they live/their name/etc) then we have three potential fathers.
Which would still allow this hypothetical woman to say, 'I do not know who the father is'.
There will be a number of women who say they don't know who the father is when they do, for various reasons. Incest is pretty low on that list, given the studies into how prevelant incest is. There's more likely things like, they're ashamed, they genuinely don't know, they cheated, it's someone they shouldn't have slept with (married man for example) and the list goes on.
However, that's still a big assumption to make that the majority are saying they don't know when they really do. It also depends on the area as well. Compare the chances in a big city, with a girl who goes clubbing and does drugs a lot, with a girl in a small town, who doesn't drink.