Out of Vietnam comes the news story that fraternal twins have been found to have different fathers!
This case came to light through a DNA test and experts are calling it an “extremely rare” case.
The twins – one reported to have thin, straight hair and the other having thick, wavy locks – recently had their DNA tested at the Center for Genetic Analysis and Technology in Hanoi, according to a scientist and a state-run news report.
Family members had been vocal about notable differences in the children’s appearance (trust family members) and so the Vietnamese couple brought in the twins for testing.
“Our Center for Genetic Analysis and Technology lab has tested and found a pair of bi-paternal twins,” said Le Dinh Luong, President of the Genetic Association of Vietnam “This is rare not only for Vietnam, but for the world.”
Indeed, medical research has shown that when a woman has sex with two men within the same ovulation window, it can result in bi-paternal twins, known as heteropaternal superfecundation.
Hilda Hutcherson, a clinical professor for obstetrics and gynecology at Columbia University, stated that fraternal twins happen when a women releases two eggs during ovulation instead of one – and both eggs are then fertilized.
With bi-paternal twins, on the other hand, each egg is fertilized by a different man’s sperm.
Eggs can live up to 24 hours in a woman’s reproductive system. Sperm, on the other hand, can live up to five days in the woman’s body, she said.
Therefore, it is possible that a woman could have sex with one man on Monday and have sex with a different man on Wednesday – and then when her eggs are released on Thursday, the two men’s sperm living inside her could each fertilize an egg.
Hutcherson said there are rare cases in which a woman may ovulate more than once during her cycle, meaning that two eggs would be released at different times.
According to Luong “There are less than 10 known cases of twins with different fathers in the world,” he said. “There might be other cases but the parents and/or the twins were not aware of it or didn’t want to announce it.”
Hutcherson said fraternal twins make up about 2 percent of pregnancies – though that number may be growing – and bi-paternal twins are a fraction of them.
“It probably happens more often than we think; it’s just that nobody is testing to see,” she said. “But it’s still extremely rare.”
Similar cases of bi-paternal twins have popped up in other countries – including in the United States.
Results showed that the mother’s DNA matched both children, according to the news agency, but the father’s did not.