A Vietnamese couple recently brought their fraternal twins to the Center for Genetic Analysis and Technologies, in the country's capital of Hanoi, to have DNA tests, after pressure from extended family members who noticed the children did not look alike, said Le Dinh Luong, president of the Genetic Association of Vietnam.
The set of twins were found to have different dads after their parents feared one may have been accidentally swapped at birth. The couple, from Hoa Binh province in Vietnam, grew suspicious after the same-sex babies, born just a few hours apart, looked completely different.
According to Dan Tri, an online news site, the family pressurised the father, 34, into getting a paternity check after one twin started to grow thick, curly hair while the other developed thin, straight hair. Concerned there could have been a mix-up at the hospital the worried parents then sent the infants, now two years old, for a DNA test.
The babies were found to be bi-paternal, meaning they share the same mum but different dads. Scientists at the Center for Genetic Analysis and Technologies in Hanoi believe it to be the country's first case of the "extremely rare" phenomenon.
President of the Genetic Association of Vietnam Le Dinh Luong said the family were shocked by the news and are trying to work out the best way to deal with the situation. Further details about the couple and the children are prevented from being made public due to a confidentiality agreement.
Bi-paternal twins can only be conceived through two acts of sexual intercourse in a reasonably short time period. This is because a woman’s egg has a lifespan of just 12 to 24 hours after being released while a man’s sperm can survive for up to seven days.
Last year a man in New Jersey was ordered to pay child support for one girl in a set of twins after DNA tests showed he was not the father of the other one.