Bingo -- the whole thing about being "cleaner for living in the desert" or something is hooey -- every desert mammal has a foreskin; if it were a disadvantage evolution would've adapted that along with all the other adaptations that desert mammals have.

That entire line is garbage and meant to support the subservience, exactly as you've said. A mother's strongest instinct is to protect her children, so the tribe taking a child and cutting his body marks him as belonging to the tribe rather than to the family. It proves, in plain view, that the familial bond is secondary, and individual autonomy serves at the pleasure of the group, not the other way around.