A sample of blood long thought to belong to French King Louis XVI is probably not authentic, scientists say.
An elaborately decorated gourd was thought to contain a handkerchief that had been dipped in the king's blood after he was killed by guillotine by French revolutionaries in 1793.
But scientists have now sequenced the genome of the sample and say it is unlikely to belong to the monarch.
Instead, the team thinks the gourd and its contents were probably the work of an 18th Century fraudster hoping to make some money from a revolutionary souvenir.
Prof Carles Lalueza-Fox, from the Institute of Evolutionary Biology in Barcelona, Spain, said: "In the French revolution, the guillotine was working every day - and probably it was much more easy to approach the scaffold when non-important people were being beheaded.
"Maybe that was one of the occasions. They thought nobody was going to be able recognise whether the blood was from the king or not."
The blood-stained cloth was stored in a hollowed-out gourd, which for the last century was in the hands of an Italian family.
The squash is decorated with images of revolutionary heroes and inscribed with text that says: "On January 21, Maximilien Bourdaloue dipped his handkerchief in the blood of Louis XVI after his decapitation."
Early forensic tests suggested it was possible that this was the blood of the French king. But this latest research casts doubt on its royal provenance.
To investigate, the scientists examined stretches of the sample's genome that relate to physical appearance.
Portraits of Louis XVI depict him with blue eyes, but this sample belongs to a person who was far more likely to have had brown eyes.
"The probability of this guy having blue eyes is very low - it is about 3%," said Prof Lalueza-Fox.
Historical records, including correspondence from Louis XVI's wife, Marie-Antoinette, also state that the king was very tall.
While the average height was about 167cm (5ft 5in) at this time, the King was thought to be at least 185cm (6ft 1in) in height.
Prof Lalueza-Fox said: "Not all the genetic basis of height is known. However, we do know the genetic markers in extreme cases for very tall people or very small people.
"But this sample doesn't have an excess of markers that could be related to a very tall person. It really looks like we don't have the king here."
The scientists also looked at genetic ancestry, which shows which parts of Europe a person's ancestors came from.
The DNA from the sample suggests the individual had roots that traced mainly back to France and Italy, while many of Louis XVI's ancestors came from Germany and Poland.
The team concludes that it's extremely unlikely that this is Louis XVI's blood.
This supports another study published last year that compared the sample to two living relatives of Louis XVI, and cast doubt on its authenticity.
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