A Vietnamese couple recently took their 2-year-old fraternal twins for DNA testing and discovered that while they have the same mother, they shockingly have different fathers.
The couple, whose names have not been released, were pressured from extended family members who noticed the children did not look alike, Le Dinh Luong, president of the Genetic Association of Vietnam told CNN.
According to the news outlet, one child has thick and wavy hair and the other has thin and straight hair.
While this is reportedly the first case of bi-paternal twins in Vietnam, a woman in New Jersey had the same revelation in May 2015.
When the mother was in the process of applying for benefits from the man she claimed was the father of the babies, a paternity test was ordered after she revealed that she had sex with another man that same week, according to The New York Times.
Results from the test revealed that he was the father – but only for one of the twins.
While it’s rare, Dr. Keith Eddleman, director of obstetrics at Mount Sinai Hospital in New York told CNN that it’s definitely possible.
A woman’s egg has a life span of 12 to 48 hours, and a sperm is viable for seven to 10 days. This makes it possible for two eggs to be fertilized by sperm from two different men during the same ovulation period.