Q: Does a person’s DNA change after...

Q: Does a person’s DNA change after a blood transfusion?

A: Not permanently, but there may be slight changes. Red blood cells, the primary component of blood used in transfusions, do not have a nucleus and thus do not have DNA. White blood cells, which are present in much smaller concentrations, do have DNA. For a few days after a transfusion, the recipient’s DNA profile might contain a small contribution from the donor blood--depending on how much was transfused-- but those cells are all cleared from the system within a month.