In 1995 Karen Keegan, mother of three, was told that she needed an immediate kidney transplant. (RadioLab, 2008) In the search for a suitable donor, her husband and her two sons underwent DNA testing. The results were shocking: her two sons'' DNA did not match hers. From a medical point of view this meant that she was not their mother. She insisted that the test be repeated since they were "obviously" wrong. She had given birth to her babies and had experienced the pain of delivery. However, the new tests confirmed the previous results. Clearly there had been no laboratory mistake. This was quite a puzzling situation, for although a mismatch between a father''s DNA and a child''s DNA is not unheard of, there had never been a case where a mother''s DNA did not match her children''s. Doctors initially thought that there was some sort of a mix up, such as switching of babies at the hospital, but then dismissed this possibility because the father''s DNA matched his sons''. Since for med
