He's asked me what makes a boy a boy and what makes a girl a girl? I told him "you have a penis, and that makes you a boy. A girl has a different body part, and that's what makes her a girl." He asked does it look different? I said yes (wrong answer!!!) he's now been asking what it looks like.
He is also wanting to know where babies come from.
How do you make a baby? (This was said in front of him by someone who said to my SIL "you're gonna make a beautiful baby")
And why does aunt sassy get so fat when a baby is coming?
How did a baby get in her belly, and how will it get out?