AOB blood grouping is the most common blood grouping in present world. In this grouping blood grouped depending on presence and absence of antigen A and antigen B in blood. Blood groups in AOB system are A, B, AB and O. I am trying to explain this blood grouping system as easy as possible so that the member of this site who has no science background can also understand the system.

If any blood contain antigen A but no antigen B, the blood group will be A blood group. If any blood contains antigen B but no antigen A, the blood group will be B blood group. If any blood contains both antigen A and antigen B, the blood group will be AB blood group. If any blood contains none of them (antigen A and antigen B ) will be O blood group.

Blood group of offspring depends on parent’s blood group. If father and mother are both bearing O blood group, their offspring’s blood group must be O. If one of them bearing A and other is bearing B blood group, offspring’s blood group may be A, B, AB or O. I am trying to describe the whole matter genetically but avoiding scientific terms as possible as I can.

Every child gets their traits (genetically transmitted traits, not all traits) from their parents. They get 50% of their traits from their father and 50% from their mother. In other word, father transmits his 50% and mother transmits her 50% to their child. Every trait is controlled by a pair of genes.
Let A blood group is controlled by “A_” gene pair,
B blood group is controlled by “B_” gene pair,
AB blood group is controlled by “AB” gene pair,
O blood group is controlled by “_ _” gene pair,

Now you can easily calculate the offspring’s possible blood group(s) if you know the parent blood group. For example, if one of them have A blood group (A_) and other have O blood group (_ _). A blood group can be divided as “A” and “_” and “O” blood group can be divided by “_” and “_” . So the possible combination of A, _ and _, _ are A _ and _ _ ie., blood group A, and O. So, if parents bearing blood group O and A, offspring blood group will be A or O not B or AB.

Another example to make this more clear, let parents blood groups are B and O. B blood group contains “B” and “_” on the other hand O blood group contains only “_” (_ _). So, the possible combination of B, _ and _, _ are “B_” and “_ _” ie., blood group B and blood group O. So the parents bearing blood group B and O will result offspring only B and O blood groups.

In this process we can calculate the possible blood group of offspring if we know the blood group of parents.

figuring out what will come out with your offsprings in punnet square.

its more easier to understand if you have a diagram of it.