Revealed: The scientific breakthroughs that could allow same–sex couples to have their OWN biological children
By JONATHAN CHADWICK, ASSISTANT SCIENCE & TECHNOLOGY EDITOR
Becoming a parent is something that many people dream of – but for gay couples, the reality can be complicated.
As it stands, same–sex partners must rely on a surrogate mother or father – but this means only one of the couple passes on their genes.
However, this could soon be about to change.
In a stunning breakthrough this week, scientists revealed they've been able to create human eggs from skin cells.
The technique opens the possibility for DNA from a man's skin cells being placed inside a donor egg, before being fertilised by another man.
In theory, this could allow two men to have a baby, without any DNA from a woman.
This is not the only cutting–edge advance in the last few years that could allow same–sex couples to have their own biological children – with other researchers looking at everything from lab–grown sperm and eggs to 'virgin births'.
So in mere decades, gay people could have a multitude of options to choose from on their journey to parenthood.
Becoming a parent is something that many people dream of – but for gay couples, the reality can be complicated
(stock image)
Sperm cell insertion
During heterosexual reproduction, genetic material carried by the sperm combines with genetic material from a female contained in the egg.
A biological baby to be born to a same–sex couple would of course have to have genetic material from both parents – from two sets of sperm, for example.
While this may sound like an impossibility, scientists in China have excitingly demonstrated that it is feasibly possible.
The experts managed to insert two sperm cells – one from each father – into a mouse egg whose nucleus had been removed.
A gene editing technique was then used to reprogram parts of the sperm DNA to allow an embryo to develop – a process called androgenesis.
The embryo (featuring the genetic material from two fathers) was transferred to a female womb and allowed to grow to term.
Finally, the resulting offspring managed to grow to adulthood and become a parent after mating conventionally with a female, suggesting that a baby born to two dads would be able live and breed as normal.
Although promising, experts caution that we are not ready to start such experiments in humans, which could be deeply unethical.
Christophe Galichet, research operations manager at the Sainsbury Wellcome Centre in London, points out that the success rate of the experiments was very low.
Of 259 mice embryos that were transferred to female mice, just two survived, grew to adulthood and then fathered their own offspring.
Genetically modified eggs
Sperm cell insertion would theoretically allow two fathers to have a biological baby, but how about two mothers?
A hallmark experiment in Japan in 2004 created the first ever 'bimaternal' mouse using eggs from two female parents.
Experts at the Tokyo University of Agriculture managed the feat by genetically modifying eggs from a female mouse to make them act like sperm.
The resulting miracle mouse, named Kaguya, was the first mammal born from two genetic mothers.
However, ethical concerns and technological limitations pose barriers to duplicating the technique in people, the experts cautioned.
These adult male mice, which each have the genetic material of their two fathers, have gone on to have offspring of their own
Human eggs from skin cells
An exciting future scenario is where anyone, man or woman, could have their genetic material in an egg.
And earlier this week, scientists offered fresh hope that such an eventuality could soon be possible.
The experts at Oregon Health & Science University revealed that they'd used human skin cells to create eggs ready for fertilisation.
The technique involves removing the nucleus from a woman's skin cell and inserting it into an egg from which the nucleus has been removed.
The breakthrough opens the possibility for DNA from a man's skin cells being placed inside a donor egg, before being fertilised by another man.
In theory, this could allow two men to have a baby, without any DNA from a woman.
While further research is needed to ensure safety and efficacy before clinical trials can go ahead, experts have described the news as a 'major advance'.
Experts from Oregon Health & Science University have created fertilizable eggs from human skin cells for the very first time. Pictured, a human oocyte with visible spindle (bright spot inside) before fertilisation
Lab-grown sperm and eggs
It sounds like something from a Mary Shelley novel, but some scientists think babies could be grown from scratch in a lab as soon as this decade.
They're pinning their hopes on in vitro gametogenesis (IVG), a new lab technology that's breaking the rules of reproduction.
IVG works by taking cells from a person's blood or skin and reprogramming them to become induced pluripotent stem cells.
In theory, pluripotent stem cells can become any cell in the body, including egg and sperm cells that could be used to make embryos and then implanted into women's wombs.
Scientists have been able to make very basic human eggs and sperm this way, but have not yet been able to make embryos.
One California–based startup called Conception is working on IVG to 'give families the opportunity to still have children at much older ages, eliminate barriers for couples suffering from infertility, and allow everyone to have biological children'.
Professor Katsuhiko Hayashi, a Japanese geneticist at the University of Osaka, expects the first viable lab–grown human sperm by about 2030.
Professor Katsuhiko Hayashi of Kyushu University (pictured), a Japanese scientist who has already figured out how to do IVG in mice, guessed it would take five years to produce egg–like cells from humans
Sperm cells from bone marrow
It was nearly 20 years ago that scientists revealed they'd used human bone marrow to create early–stage sperm cells for the first time.
The experts from the UK and Germany took stem cells from the bone marrow – the soft, spongy tissue in the centres of bones – of male volunteers.
Usually, such samples would be developed into cells that form part of muscle tissue, but the team developed them into spermatogonial cells, which become mature sperm cells.
The 2007 achievement heralded the possibility of using 'artificial sperm', removing men from the process of creating life.
In theory, one member of a lesbian couple could used their bone marrow sample to grow sperm that could fertilize their partner's egg.
Scientists said their next goal was to get the spermatagonial stem cells to progress to mature sperm in the lab, although it's unclear if they're still working on this.
Their paper, published in the journal Reproduction: Gamete Biology, was redacted two years later due to claims of plagiarism.
Today, gay couples who want to have children usually rely on a surrogate mother or father to bring a child into the world (file photo)
Virgin births
In the animal kingdom, a seemingly miraculous phenomenon of Biblical proportions exists in nature that offers hope to millions of gay couples.
Known as parthenogenesis or virgin birth, it allows a baby to be born without any kind of sexual intercourse.
Parthenogenesis usually happens when the female has been isolated for a long time and has little hope of finding a male to mate with.
By this logic, women who are living alone should be able to get pregnant even if they are not having sexual intercourse with a man.
Virgin births have been observed in sharks, snakes, crocodiles, crustaceans, scorpions and wasps – but scientists say they might be possible in humans.
Dr Louise Gentle, lecturer in zoology at Nottingham Trent University, said parthenogenesis in humans is 'technically possible', but it would require humans with similar genetic tweaks or mutations to breed together.
'To get parthenogenesis in humans, you would need to have individuals with the same chance mutations (there would have to be many mutations) breeding together,' she said.
Just a few years ago, parthenogenesis was thought to be impossible in mammals – but recent experiments have changed all that. Scientists in China reported in 2022 that parthenogenesis had been achieved with mice using the clever but controversial gene–editing tool CRISPR
'It's an extremely long shot, with a tiny probability, but it is technically possible.'
Likewise, Tiago Campos Pereira, a professor of genetics at the University of São Paulo in Brazil, said there are 'biological barriers' established by our genetic makeup that prevents parthenogenesis in humans.

But this genetic makeup may be 'altered by natural mutations', he told the Daily Mail.
All babies born due to parthenogenesis are essentially 'identical' genetic clones of their mother right down to their sex, but long–term this could be disastrous for the survival of a certain species due to a lack of genetic diversity.
Would it be worth it?
Lluís Montoliu, a biotechnologist based in Spain, said such procedures would 'revolutionize fertility treatments' if they were ever to successfully and safely produce human embryos.
He said such methods could potentially 'be optimised to the point where we can consider offering them in fertility clinics'.
'For the moment, these human applications remain in the realm of science fiction,' he said in a piece earlier this year for The Conversation.
'We must ask ourselves, as a society, whether we would be willing to ethically and legally accept these techniques.'
HOW DOES CLONING HAPPEN IN NATURE?
Asexual reproduction – when an organism reproduces without fertilisation – only requires one parent, unlike sexual reproduction, which needs two parents.
Since there is only one parent, sec cells (sperm and eggs) don't fuse and no genetic mixing takes place.
Because of this, the offspring of asexual reproducing organisms are genetically identical to the parent and to each other – they are clones.
For instance, female marble crayfish can induce her own eggs to start dividing into embryo .
Normal sex cells contain a single copy of each chromosome. But the mutant crayfish sex cell has two.
The two sex cells fuse and produce a female crayfish embryo with three copies of each chromosome instead of the normal two.
Some other examples of organisms that can clone themselves include:
- Cockroaches
- Aphids
- Hammerhead sharks
- Jellyfish
- Marmokrebs (marbled crayfish)
- Desert grassland whiptail lizards
- Gall wasps
- Komodo dragons
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Researchers based their findings on clam shells recovered from around the North Atlantic region. In this colour map, redness indicates greater loss of current stability preceding rapid circulation changes
What is the North Atlantic Subpolar Gyre?
The North Atlantic Subpolar Gyre is a massive system of rotating ocean currents in the North Atlantic.
It transports heat from the tropics to the North Atlantic, helping to regulate temperatures in Europe and North America.
It also helps to power the Atlantic Meridional Overturning Circulation (AMOC) – a key part of the global ocean conveyor belt that moves heat and nutrients around the world.
'We don't have ocean observations going back into the distant past, but the bands in clam shells give us an unbroken annual record covering hundreds of years,' said Dr Nava.
The data revealed that the North Atlantic Subpolar Gyre has had two 'destabilisation episodes' over the past 150 years where it has lost stability – suggesting that a tipping point could be approaching.
The first destabilisation episode happened in the early 20th century before the 1920s, while the second stronger episode began around 1950 and continues to the present day.
This suggests that the North Atlantic Subpolar Gyre is moving toward a tipping point that could lead to a cascade of 'catastrophic, irreversible changes' to our climate, such as more extreme weather events, particularly in Europe, and changes in global precipitation patterns.
While it would be less catastrophic than the collapse of the AMOC, it would still bring substantial impacts including more frequent extreme weather in the North Atlantic region and deep freezes in Europe.
The UK and northern Europe could experience much harsher winters typical of parts of Canada, while the east coast of the US could see dramatic sea level rises due to changes in ocean circulation.
While the North Atlantic Subpolar Gyre looks likely to 'weaken abruptly', it 'would not completely collapse' as it is also driven by winds, Dr Nava said.
North Atlantic Subpolar Gyre is part of, and helps power, the Atlantic Meridional Overturning Circulation Earth's vast system of ocean currents that distributes heat and nutrients around the world. The new study finds evidence of 'stability loss' that suggests the region is 'moving towards a tipping point'
The Little Ice Age was a period of major mountain-glacier expansion that spanned from around the early 14th century through to the mid-19th century, when rivers froze over and crops were decimated
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'Such a weakening would reduce the northward flow of heat carried by ocean currents, likely triggering a chain of climate changes including more frequent extreme weather events, stronger seasonal contrasts in Europe, and shifts in global rainfall patterns,' she told the Daily Mail.
However, a weakening North Atlantic Subpolar Gyre is what occurred during the early years of the Little Ice Age – suggesting similar climate effects could be seen again even if the wider AMOC doesn't collapse.
The study, published in the journal Science Advances, offers independent evidence that the North Atlantic has 'lost stability over recent decades and is vulnerable to crossing a tipping point'.
'Melting of polar ice due to climate change is certainly contributing to the weakening of ocean currents and pushing them closer to a tipping point, so rapidly reducing greenhouse gas emissions is the best way to prevent tipping points in the Atlantic Ocean,' the expert added.
How does global warming affect global currents?
Scientists think melting glaciers could cause the collapse of the Atlantic Meridional Overturning Circulation or AMOC, the system of ocean currents.
Described as 'the conveyor belt of the ocean', the AMOC transports warm water near the ocean's surface northwards – from the tropics up to the northern hemisphere.
When the warm water reaches the North Atlantic (Europe and the UK, and the US east coast), it releases the heat and then freezes. As this ice forms, salt is left behind in the ocean water.
Due to the large amount of salt in the water, it becomes denser, sinks, and is carried southwards – back towards the tropics – in the depths below.
Eventually, the water gets pulled back up towards the surface and warms up in a process called upwelling, completing the cycle.
Scientists think AMOC brings enough warmth to the northern hemisphere that without it, large parts of Europe could enter a deep freeze.
Prior studies have already shown that due to climate change, the AMOC is weakening (meaning the movement of heat is slowing down)
The engine of this conveyor belt is off the coast of Greenland, where, as more ice melts from climate change, more freshwater flows into the North Atlantic and slows everything down.