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

Dad’s genes must be – O+ and O-. Mom’s genes – at least one B gene, possibly two. If two B genes, then it’s B+ and B-. If it’s just one B gene, if it’s B+, then the other gene is O-, and if it’s B-, then it’s O+. The genes for blood type and rhesus factor code separately.

This assumes you are the biological child of these people.