Doctors have confirmed that a pair of twins born in Vietnam have different fathers, effectively making them half-siblings.
The children's parents initially became suspicious when their extended family pointed out that one of the twins (now two years old) grew thick curls while the other had thin, straight hair.
Worried they may have taken the wrong child home from the hospital, the concerned couple ordered a DNA test.
Now scientists at the Center for Genetic Analysis and Technologies in Hanoi, have confirmed the twins are bi-paternal; they have the same mother but different fathers.
Bi-paternal twins are extremely rare and occur when a woman releases two eggs (which can stay viable for 24 hours after ovulation). Because sperm can potentially survive up to five days inside a woman’s body, it stands to reason that a woman could get pregnant twice during that time.
But just because you know some twins who don't look alike, don't go jumping to any conclusions: studies estimate that fewer than one in 400 sets of fraternal twins (already rare) is bi-paternal.
