Mice with two biological fathers have their own offspring for the first time

For the first time, scientists have managed to create healthy, fertile mice, from two biological fathers, that have gone on to have their own offspring.

The research, published on Monday (23 June) in the scientific journal PNAS, revealed that two healthy, fertile “bi-paternal” mice, whose genetic material originated from two males, had been created.

The health and fertility of the bi-paternal mice could have implications for human same-sex parents in the future – helping two men to have genetic children of their own – but experts have said it would be “unthinkable” to translate the experiments into human testing any time soon.

While mice with two mothers and no father hit the news in 2004, and mice with two biological fathers were created two years ago, this is the first time mice born to two fathers have gone on to have their own pups.

A team at China’s Shanghai Jiao Tong University, led by Yanchang Wei, managed to create the bi-paternal mice by putting two sperm cells together in an egg whose nucleus had been removed. The scientists then used a gene-editing technique to “reprogramme” parts of the sperm DNA to allow an embryo to develop. The embryo was then implanted into a surrogate female mouse, eventually resulting in the births.

Two pups of the 259 embryos that were created survived and grew into adulthood. The bi-paternal mice, both male, then mated with female mice after growing into adulthood, and fathered the healthy pups of their own.

“In this study, we report the generation of fertile androgenetic mice,” the scientists said. “Our findings, together with previous achievements of uni-parental reproduction in mammals, support previous speculation that genomic imprinting is the fundamental barrier to the full-term development of uni-parental mammalian embryos.”

Earlier this year, a separate team in China reportedly managed to create a few bi-paternal mice that grew into adulthood, but they were not fertile.

Christophe Galichet, the research operations manager at the Sainsbury Wellcome research centre, told the New Scientist: “While this research on generating offspring from same-sex parents is promising, it is unthinkable to translate it to humans due to the large number of eggs required, the high number of surrogate women needed and the low success rate.”

In addition, the effects of making genetic changes aren’t yet fully understood, the magazine reported.

Despite this, a molecular geneticist at University College London said: “It confirms that genomic imprinting is the main barrier to uni-parental reproduction in mammals and shows it can be overcome.”

However, there was opposition to the research from animal rights organisation People for the Ethical Treatment of Animals (PETA), with a spokesperson calling the research “rainbow-washed”.

Jeffrey Brown, PETA’s science advisor, said: “This isn’t ground-breaking, it’s grotesque. Real progress lies in cutting-edge, human-relevant, non-animal methods.”

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