At Christmas we are asked to believe in miracles. Misers suddenly becoming philanthropists, a man too fat to get down chimneys globetrotting with a load of reindeer and a virgin giving birth. The last one is hard to believe.

Even Mary is reported as having complained to the rather alarming messenger (with wings and bearing lilies): “How can this be? I am a virgin.” And surveys suggest rising numbers of nonbelievers among Church of England clergy (33 per cent, up from 25 per cent a decade ago). The irony is that today’s reproductive medicine actually makes virgin birth highly feasible.

If, for you, theological miracles need no explanation, look away now. For everyone else: virgin birth is a familiar phenomenon in nature. Birds do it, bees do it, but my inquiries as to whether educated fleas do it have regrettably drawn a blank. Greenfly have it down to a fine art, filling your roses with hosts of their number through a process known as parthenogenesis.

The zoological definition is the development of an egg into an embryo without the participation of a sperm, and greenfly produce brood after brood of female offspring before accepting males into their number for overwintering.

The keen-eyed will have already spotted a wrinkle here. Jesus should by rights be a girl, though the appellation “son of God” seems clearly to suggest maleness.

And there is another problem. These examples are all of lower-order creatures. In 1958, however, a Russian scientist claimed to have found colonies of all-female lizards living in Armenia. Subsequent investigation revealed that some whiptail lizards, certain Komodo dragons (since you ask, one called Flora who lives in Chester Zoo) and other higher-order animals such as bonnethead sharks and even turkeys, can do the virgin birth thing.

Mammals? Unfertilised mouse eggs can be induced to develop into embryos but then die, but more of this anon.

The Lancet printed a “virgin birth” story

In humans, eggs occasionally do develop in the absence of sperm but, instead of forming a baby, the end product is something known as a teratoma, a rather creepy tumour which is full of hair and teeth. Nevertheless there are persistent reports of virgin birth in the case literature.

In 1874, for instance, the American Medical Weekly published an extraordinary story from the diary of a field surgeon during the Civil War. His notes told of a soldier he attended who had been shot in the leg; the bullet had ricocheted off the bone and carried away his left testicle before lodging itself in the stomach of a woman standing behind him. Some 278 days later, the same surgeon delivered a baby to this woman who continued to maintain that she was a virgin. The Lancetreprinted the story several months later and in 1959, it popped up in the New York State Journal of Medicine, this time under the heading “Two unusual cases of gunshot wounds to the uterus”. An appearance in not one but three proper medical journals has caused many since to quote this case as cast iron evidence. So, a genuine virgin birth?

Virgin on the ridiculous more like. If the name of the author of the 1874 piece isn’t enough (Capers), there is also some deeply implausible detail – such as the army surgeon finding the bullet lodged in the scrotum of the baby. It proves the old maxim – if hoaxing, lay off gilding the lily.

Then there is the curious case of the 19 virgins. In 1955, a geneticist called Helen Spurway from University College London, wife of the famous biologist J. B. S. Haldane, had reported that female guppies in her laboratory aquarium were giving birth to young fish in the absence of males. She speculated that although it would be very rare, it might be possible in humans and moreover could be proved using the rudimentary science (as it was then) of genetic testing.

The boy who had no father

A now defunct tabloid newspaper, the Sunday Pictorial rose to the challenge and advertised for women with children who thought they were virgins (as you do) to write in.

Astonishingly 19 women did so, 11 of whom were subsequently immediately rejected by the investigator, one S. Balfour Lynn, since they had all been impregnated by men, but believed that because their hymen remained intact after conception, they counted as virgins. The remaining mothers and daughters were investigated for genetic similarity. Genuine virgin births should mean they were identical. One pair seemingly was but later a skin-graft operation between them was eventually rejected, meaning that there must have been differences.

Finally, there is the case of the boy whose blood showed he had no father. Reported in 1995, this was the case of a young boy, part of whose body was shown to be derived from an unfertilised egg. His blood cells contained two XXs, the chromosomal signature of a female, but both Xs in this case were shown to be derived from his mother. His skin on the other hand contained X and Y chromosomes typical of a boy, the Y having come from his father.

There have been many attempts, notably by another distinguished UCL geneticist, the emeritus professor Sam Berry, to put forward possible mechanisms. “Not to suggest an explanation or way of avoiding belief in the Virgin Birth,” says Berry, a committed Christian, “but merely to suggest that the Virgin Birth is not utterly ridiculous from the biological point of view.”

The problem with virgin birth and the Christmas story is that Jesus is a boy – which suggests he must have a Y chromosome. Creating a scenario as to how this might be biologically possible requires a fair bit of biological imagination and the occurrence of some rare-to-almost-never-heard-of medical conditions.

Among Berry’s suggestions is that Mary, while outwardly appearing female, could have actually been genetically male (ie carrying a Y chromosome) because of a syndrome called testicular feminisation and been one of the rare examples of sufferers who also still had a womb and had numerous other variations of it which could produce a male baby.

Confused? I’m sure Mary would have been.

Veritable virgins

Ever since Dolly the Sheep appeared, virgin birth has technically been possible. A clone involves taking the genetic material out of a male or female adult cell, placing it in the empty egg of another individual and giving it a small electrical kickstart before replacing it in a womb. Many species have now been cloned, from mice to rhesus monkeys.

High failure rate

Cloning is an inefficient process, with a very high failure rate and there are many reports of abnormalities in cloned animals that require them to be put down straight after birth. Human cloning is not thought to be possible currently.

Divine DNA?

Virgin birth might be technically feasible, but it would be highly dangerous and is likely to be illegal for many years to come. The burning question is: how you would get God to supply his genetic material?

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