How Is Blood Type Determined?

Blood types are determined by the presence or absence of particular antigens on the surface of red blood cells. There are eight main blood types: A positive, A negative, B positive, B negative, AB positive, AB negative, O positive and O negative. The positive and negative refers to your Rh type (once called Rhesus).

How is blood type genetically determined?

Just like eye or hair color, our blood type is inherited from our parents. Each biological parent donates one of two ABO genes to their child. The A and B genes are dominant and the O gene is recessive. For example, if an O gene is paired with an A gene, the blood type will be A.

Can a child have a different blood type than both parents?

Yes, a child is able to have a different blood type than both parents. Which parent decides the blood type of the child? The child's blood type is decided by both parents' blood type. Parents all pass along one of their 2 alleles to make up their child's blood type.