Blood Group Inheritance in Humans

Every one is born with genes inherited from our parents. The blood group depends on the combination of a pair of genes, one of which is inherited from each parent.

There are four blood groups - A, B, AB and O. Every human being has one blood group out of the four. The genes which control the inheritance of these blood groups are designated as IA, IB and i. When a foetus (growing young one in mother’s womb) develops, its blood group is determined by the combination of any of the two genes, one received from each of the parents.

The combination of genes and the resulting blood group:

Gene Combination Blood Group
IA IA or IA i A
IB IB  or  IB i B
ii O

Gene IA and IB are dominant and i is recessive. Apart from these blood groups, human beings may also belong to the groups designated as Rhesus positive (Rh+) or Rhesus negative (Rh-). Most humans are Rh+. Some are Rhesus negative. The Rh+ gene is dominant over Rh- gene.

Why should you know your blood group?

In case of any emergency such as an accident, or a diseased condition, blood transfusion may be required. Only a matching blood group of the blood donor can be transfused. A person with blood group A can donate blood to patient with blood group A and AB. AB can receive blood from any of the four blood groups.

O can receive blood only from O but donate blood to all four blood groups. Sometimes there may not be time or facility available for prior ascertaining of the blood group. Immediate blood transfusion is possible if the blood group is known. If unknown, the safest blood group for transfusion is O negative (O group and Rh-). B can donate to B and AB. O is the universal donor and AB is the universal recipient.