A Portuguese teenager has welcomed a set of twins with two different dads.
The woman, who chose not to be named, is from the Portugese town of Mineiros and recently welcomed her two little boys into the world.
However, the 19-year-old was gobsmacked when DNA tests from the man she presumed to be their father only came back positive for one of her sons.
She told local media that she’d had sex with two men on the same day, but ‘didn’t know this could happen’.
The new mum explained: “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."
It’s thought to be only the 20th case of hetero-parental superfecundation - when the eggs are fertilized by the sperm from different men - ever recorded in the world.
Although the babies have two different dads, only one man will be registered on the birth certificate.
The young mum shared: "He takes care of both of them, helps me a lot and gives them all the necessary support that they need."
Dr Tulio Jorge Franco, an expert in the field, offered some insight into how such a pregnancy can happen and just how rare it is.
He told G1: "It is possible to happen when two eggs from the same mother are fertilised by different men.
"The babies share the mother's genetic material, but they grow in different placentas.
"It's extremely rare. It happens one in a million. I never imagined that I would see a case like this in my life."
Franco added: "The pregnancy was super smooth, without any complications. The boys were born healthy and never had health problems."
Last month, mum Chantelle Broughton, 29, was left stunned when she gave birth to twins with totally different skin colours.
The tots are so rare that genetics experts estimated them at one in a million.
Chantelle welcomed son Ayon and daughter Azirah into the world back in April, with Ayon being born with green eyes and fair skin while Azirah has brown eyes and a much darker complexion.
The mum-of-three revealed the twins didn’t look too different from each other at birth, but as the weeks went by, Azirah's skin complexion started getting 'darker and darker'.
Chantelle also explained that although she looks white, she’s actually mixed race and has a Nigerian maternal grandad, whereas dad Ashton, also 29, is half Jamaican, half Scottish.