My father had blood group B positive Rhesus D+, my mother A positive Rhesus D+, how come I have 0 positive Rh D+?

Answer

Dear Daniel,

It is perfectly possible that your father was B+ and your mother was A+ and that you have blood group O+.

Your blood type is always determined by DNA from your father and your mother. So you are 50% dependent on your father and 50% dependent on your mother.

They are also dependent on their parents.

Let’s stick to blood groups A and B.

If you inherit the gene for blood group A from one of your parents, you have blood group A

If you inherit the gene for blood group B from one of your parents, you have blood group B

If you get the gene for blood group A from one of your parents and the gene for blood group B from the other, you have blood group AB.

If you don’t get the gene for A or B, you have blood group O

So you did not inherit the genes for blood group A and B from your parents. That is, your father had only 1 gene for blood group B and your mother had only 1 gene for blood group A.

Your father had the genes: B and O and your mother had the genes A and O (O is not a gene, but for simplicity I present it as a separate gene)

Your father and mother both passed their O to you.

kind regards,