Is it possible to switch blood types

It is not possible to switch blood types.

Explanation:

Blood type is hereditary. That is it is being transferred from the parents to the offsprings. Blood type is inherited by the offspring from the parents at the point of fertilization of the egg by the spermatozoa. There are basically four blood types: A, B, AB and O. These blood types or blood groups are named on the basis of the type of antigens they have. There are two types of antigens: antigen A and B. Blood type A has only A antigen, blood type B has only B antigen, blood type AB has both antigen A and B while blood type O has no antigen.