A set of twins born to a Vietnamese couple, whose names have not been released, were recently taken for testing because of stark differences in the children’s appearances, according to local reports.
The Vietnamese couple was shocked to hear that only one of their twins was biologically related to the father.
Both were, however, the offspring of the mother – with tests ruling out the possibility of a hospital mix-up shortly after their births.
Le Dinh Luong, President of the Genetic Association of Vietnam, told AFP that the findings were extremely rare.
“Our Centre for Genetic Analysis and Technology lab has tested and found a pair of bi-paternal twins.
“This is rare not only for Vietnam, but all over the world.
“This can happen if two eggs from the same mother are fertilised by sperm from two different men during separate acts of sexual intercourse within the same ovulation period.’’
According to the report, the Vietnamese husband requested genetic testing at the Hanoi lab to determine whether he was the biological father of his wife’s twins.
The man’s relatives pressured him to take the test because one of the babies looked strikingly different from him than the other child, AFP reports.
The test results indicated that the man was related to only one of the babies.
The twins are reported to be of the same sex, born just a few hours apart on the same day, but look completely different.
They are now two years old and one of them has thick, wavy hair, while the other has thin, straight hair.
Another rare case of bi-paternal twins was reported in the United States last year.
A court ruled that a man was only required to pay child support for one girl in a set of twins after DNA tests proved he was not the father of both babies.