Can identical twins have different blood groups?

Each of these twins is the result of a separate egg being fertilized by a separate sperm. So whatever is true for brothers and sisters, is true for fraternal twins too. And since brothers and sisters can have different blood types, so too can fraternal twins. It is a different story if the twins are identical. read more

Monozygotic twins are identical twins and have therefore the same blood type. THe only exception I could imagine is in case of postzygotic mutation. in this case identical twins can develop non-identical characteristics. read more

Brothers and sisters can have different blood type same way fraternal twins can have different blood types . In fact the whole family can have different blood group, Yes if they are fraternal twins and, although much less common, it is also even possible if they are identical twins. read more

The other twin is still Type A, so you have identical twins (MZ/MC) with two different blood types: one A and the other O. If you start with a zygote that has Type B blood and wish to inactivate the B allele, it is even less probable, because it requires mutations at 7 places in the gene to render it inactive. read more