Both of my parents have rhD positive blood. I came out with rhD negative blood. How?

Question

Mum: O+
Dad: B+
Me: O-

In: 673

Answer 1

My best friend (brown hair, brown eyes) and his wife (brown hair, brown eyes) have 4 children. Two of the kids look like them.

I have (blond hair, blue eyes), so do two of their kids.

More than one person has accused me of being the *milk-man*.