The couple feared there had been a mix up at the fertility clinic Getty Images A US man has failed a paternity test after doctors revealed his dead twin, whose DNA the man absorbed in the womb, is the genetic father of the child. The 34-year-old man is the first ever reported case of a paternity test being fooled by a human chimera, someone with extra genes absorbed from a twin lost in early pregnancy. Approximately one in eight single childbirths are thought to start as multiple pregnancies and occasionally cells from the miscarried siblings are sometimes absorbed in the womb by a surviving twin. According to Buzzfeed , the Washington couple took a paternity test after their son’s blood type didn’t match that of either parent. After having a child with the help of fertility clinic procedures, they feared that sperm donors may have potentially been mixed up.  Science news in pictures After the initial failed fertility test, they took a genetic ancestry test which suggested that the man was actually his son’s uncle. The father’s sperm was found to have 10 per cent of a genetic match to the infant. The genes in his sperm were different to that in his saliva and it has been concluded that the father of the boy is effectively the man’s own unborn twin.