Awkward. Scientists in Vietnam have confirmed an extremely rare case of bi-paternal twins, or twins who have two different fathers. A Vietnamese couple brought their two-year-old twins for DNA tests when they began to look strikingly different, with one child growing thick wavy hair while the other had thin, straight locks. President of the Genetic Association of Vietnam, Le Dinh Luong revealed that the couple felt pressure from extended family members to get the children's DNA checked, with the parents even wondering whether there had been a mix-up at the hospital. However, tests showed that there was no mix up and that the children had the same mother, but different fathers. According to Vietnam's state-run news agency VNS, the mother's 34-year-old husband was father to one of the twins but not the other. Explaining how such an incident can happen, Dr. Keith Eddleman, director of obstetrics at Mount Sinai Hospital in New York told CNN: "A woman's egg has a life span of 12 to 48 hours, and a sperm is viable for seven to 10 days, so there's about a week's time for potential overlap and the fertilization of two eggs by two sperm from separate acts of sexual intercourse". Yikes.