Hint: It's not paternal instinct

While patriarchy upholds the power of men as a class, the reality is that the average man holds little power in the world. Male socialization views the world in terms of hierarchy: as long as he is below someone, he is powerless. In patriarchal terms, this defines someone as "weak". Most men are constantly reminded of their low ranking in the hierarchal scheme. However, if someone is below him, he is powerful. You can probably see where I'm going with this.

By fathering children and creating a family unit, men can finally cash in on a little bit of power. No matter his status in society or who orders him around at work, at home he can exercise ultimate control over his partner and children. Finally, he can be the highest ranking person in the hierarchy, even if he ain't shit.

A comment on my previous post gave me a lightbulb about this, and bell hooks also discusses this in The Will To Change.