Okay, so I was watching the Simpsons earlier this evening with my g/f, when she turned to me and asked "How come the Simpsons kids all have spiky hair, but nobody else in the family does?"
I thought about it, and realized she was right.
Homer, when he was younger, had brown hair, combed back, then went balder with each addition to the clan.
Marge always had blue hair, straight when she was younger, or piled up high as it is now.
Grandpa Abe had a brown buzzcut back when he was in the army, and now he has a blondish tuft.
Homer's mum (can't remember her name) had black hair styled like a beatnick back in her hippy days, and a grey coiffure later.
Marge's dad had black curly hair if I remember correctly, and her mum had a similar style to Marge's but not stacked as high.
Patty and Selma don't have spiky hair either.
This makes us suspect Marge of infidelity. Bart, Lisa and Maggie may possibly be illegitimate!