Which is why logically, kids should take the surname of the mom rather than the dad. Afterall....you know who your mom is....she tells you who's the dad!
In other words: we have some random but inconclusive studies and 1/25 is a number we pulled out of the air, but it sounds good and is a recognizable number and people will read the article and chat about it at the water cooler.
I have a friend who had a one night stand found out he had a kid five years after the fact, and the woman told a different guy her boyfriend it was his and he believed it for about four years. Sometimes its not a one night stand. I have another friend who works with a guy who was the victim of a woman who knew he wasn't the father of her kid and he didn't find out till the kid was four or five. What's worse in the situation is that the girl's family knew the secret and her sister was the one to finally tell him. Pretty sad situation because the guy had to let go of this kid he thought was his for a few years and it was hard for him but he had to.