Is there a primal drive in most people though? I do not think any of my friends in high school or in college had any great longing of becoming a father - did you? They had plenty of other drives, though. So if this primal drive you speak of exists, it must somehow appear out of seemingly nowhere - indeed out of aversion - after one's mid 20. And the mechanism for that eludes me. What sort of hormonal changes lead to it? Is it a gradual change, or do you wake up one morning and think 'God, you know what I'd really love? To be looking after a baby!'