1) ""No, a person who received a whole blood transfusion would not display detectable amounts of the donor's DNA profile." Due to certain limitations, whole blood transfusions are rare; most blood transfusions today are done with what's called packed red blood cells, a.k.a. erythrocytes, which perform the function of transporting oxygen and carbon dioxide to and from the cells of the body. Erythrocytes contain no DNA, however, having lost their nuclei during maturation. Hope you were paying attention, 'cuz we'll revisit this later. Packed red blood cells are just that; it contains almost nothing else. This is different from whole blood, per se, which contains other components, such as serum, white blood cells, platelets, and antibodies. White blood cells, a.k.a. leukocytes, contain nuclei and are the agents that provide a DNA profile from blood. In whole blood transfusions, the whole soup is transfused from one person to another. Be that as it may, in actual observation, the DNA profile of a blood donor has not been detected in the peripheral blood of a recipient, regardless of how much was transfused. In one study, a woman was transfused with 14 units of blood (four whole, ten packed red cells), while a man received 13 units (four whole, nine packed red cells). In both cases, neither individual had detectable levels of the foreign DNA profile, despite being tested as late as the following day. Since the average man has ten to twelve pints of blood and the average woman has eight to ten pints, you'd think there'd be something detectable, despite a complete hematological overhaul-and-then-some." Source and further information: http://www.straightdope.com/mailbag/mblood.html 2) " If someone were to require a whole blood transfusion, the donor's white cells would enter the recipient's bloodstream and remain there until they expire, generally within 4 to 8 days. Such whole blood transfers are very rare, however, and the donor's DNA would not survive long enough to have an effect on the recipient's DNA. Conceivably, a blood test taken shortly after a whole blood transfusion could show a mix of DNA coding, but not strictly the DNA of the donor." "receiving a standard platelet, plasma or red cell blood transfusion will not change the recipient's DNA at all. Receiving a whole blood transfusion might skew the results of a DNA test for a few days, but eventually the recipient's own blood cells should overwhelm those of the donor. Only a systemic process such as bone marrow transfusion could actually change the DNA profile of a recipient." Source and further information: http://www.wisegeek.com/can-getting-a-blood-transfusion-change-my-dna.htm 3) Further information: - "What happens to your DNA after a blood transfusion?" http://www.whfhhc.com/Blood-Transfusion/85921.htm - "Bloody Transfusions and DNA" http://www.theanswerbank.co.uk/Science/Question360018.html