Confused

[zacandtess]

My Dad is O+ and my Mum is A2B+ but my blood type is B-. How is this possible?

[Penyair]

There are many blood types.  Most of us think of A, AB, B, and O.  We generally know people are RH neg or pos.  But some people are RH neutral.  Meaning sometimes the RH seems opposite.  There is also something known as a universal donor and a universal recipient.  This can also affect a babies blood type.  If one of your parents have had a bone marrow transplant it might seem weird.

I have a condition known as chimerism.  This made my own blood type odd.  I've had a daughter with A neg and a son with B positive.  My body was one of the few with two blood types.  Universal Donor and Recipient.  I've also had a bone marrow transplant from stem cells from my A positive twins(in the 70s) when I had leukemia which cured it.