Here's another geek's response:
Classic... So will married bliss kill my hacker mojo?
I think the mechanism here isn't the oversimplified, "competitive edge among young men to fight for glory and gain the attention of women." That would imply that only men lose their creative edge when their priorities shift.
A broader look at the subject would show a parallel with a more modern topic: anti-depression medications. There are plenty of examples of highly creative people -- geniuses in their fields -- whose creativity would likely have been quashed if they'd had access to a good Selective Seratonin Reuptake Inhibitor. Poet Emily Dickinson and artist Vincent Van Gogh come to mind, but I'm sure there are many others.
The problem, as I see it, isn't that having a family takes something away from a would-be genius... any more than an appropriate dosage of Prozac does. What both do, ideally, is give the person a sense of contentment, a feeling that things are the way they should be.
Further, having a family necessarily entails a loss of focus - instead of concentrating on a problem 16 hours a day, one's time becomes split between work, spouse, children, mortgage, etc. This loss of focus is often welcome since it is an almost natural result of finding love.
Creativity, in the end, often requires adversity to bring it out. Remove the adversity, and the creativity (or "genius") may seem to be extinguished. But there are examples such as Bach, Hawking, etc that show that it is possible to achieve both genius and happiness. It just doesn't happen very often.