How can twins share DNA from two fathers? One in a million case baffles doctors

A Portugal woman has revealed recently that her twin children has DNA of both sex partners with whom she had sex on the same day.

Now one year and four months old, these twins were tested for their DNA and the doctors were surprised to see that both of them had the DNA of both fathers.

The woman, who preferred not to be identified, said after having sex with them on the same day, she became pregnant with the twins. The woman hails from the town of Mineiros in the state of Goias in Portugal.

What’s heteroparental superfecundation?

The case has become what the medical doctors said was the rarest of the rare 20th case of ‘heteroparental superfecundation’ ever recorded in the world.

Representational picture of twins / https://www.womenshealth.gov/

It means a pregnancy that produces twins with two different fathers. Dr Tulio Jorge Franco, who has been studying the unusual pregnancy since the beginning said, “two eggs from the same mother are fertilized by different men. The babies share the mother’s genetic material, but they grow in different placentas”.

According to Jason Kasraie, the chair of the Association of Clinical Embryologists, a woman can release two eggs at the same time. Since sperm can survive for a few days in the female reproductive tract, loitering in the corner of the womb and the fallopian tube, it would be possible to have sex with one father-to-be in advance of the egg being released, and another just after ovulation.” Or it could be possibel when the woman releases two eggs a few days apart but in the same reproductive cycle.

It was realized only when one boy’s DNA did not fully match with the father, one of the two men who fathered the twins. The woman recollected: “I remembered that I had had sex with another man and called him to take the test, which was positive… I was surprised by the results. I didn’t know this could happen and the babies are very similar.”

However, the birth certificate of both of them is in the name of one father and “he takes care of both of them, helps me a lot and gives them all the necessary support that they need,” she told media.

Doctor confirms

Dr Tulio Jorge Franco recently confirmed the details in a talk with the Portuguese news outlet G1. “Two eggs from the same mother are fertilized by different men. The babies share the mother’s genetic material, but they grow in different placentas,” he explained.

He further added that it is an extremely rare case that happens once in a million. “I never imagined that I would see such a case in my life,” he noted.