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

RHD+ is a dominant trait. This means that if you have one + and one – copy of the RHD gene, you will always be RHD+. If two such people with mixed genetics have a kid, there’s about a 25% chance that their kid inherits both – copies which makes them RHD-.