Rubbish. "Barring other factors" is a qualification big enough to drive a tractor trailer through, filled with millions of counter-examples on both sides. Many

Rubbish. "Barring other factors" is a qualification big enough to drive a tractor trailer through, filled with millions of counter-examples on both sides. Many fathers love their mate for life or at least decades. Many others abandon her before the child is born. Whatever explains this variance is not biology. What evidence point to 4 years as normative? What evidence suggests that a 4-year-old doesn't need a father? "OK, kid, I see you're walking and making sentences. Here's a knife and some flint. Good luck."