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

Mom’s actual genes are: OO+-. This expresses as O+.

Dad’s actual genes are: BO+-. This expresses as B+.

Your odds of coming out O- with this combination was 12.5%.