It seemed like the perfect forensic tale. Earlier this year, a geneticist concluded that the remains of a blood-soaked cloth stored for centuries in an 18th century gourd likely belonged to the severed head of the last French king, Louis XVI—a conclusion supported by the fact that the DNA matched that taken from a mummified head belonging to his direct ancestor, King Henry IV. So confident were some people about the findings that a company now offers a blood test for anyone who wants to see if they, too, are descendants of this royal family.
But new research released today calls into question the identities of both the blood and the head, arguing that the DNA in those samples does not match the DNA in living relatives of these kings. The data “make a strong case,” against the previous work, says Cristian Capelli, a geneticist at the University of Oxford in the United Kingdom who was not involved with the work.
Geneticist Carles Lalueza-Fox from the Institute of Evolutionary Biology in Barcelona is the one who matched the DNA of the blood soaked cloth by isolating a small amount of the Y chromosome.
French historian Philippe Delorme wasn’t convinced. There was so little Y chromosome from the head that the matchup could have been by chance. He teamed up with geneticist Jean-Jacques Cassiman from the Catholic University of Leuven in Belgium and identified three living descendants of the French kings, members of the House of Bourbon, to find out what the Y chromosome of that lineage should look like. They analyzed the Y chromosomes of these male relatives, and came up with a “Bourbon” Y chromosome profile. That profile did not match that obtained from the blood and head, Cassiman, Delorme, and their colleagues report today in the European Journal of Human Genetics.
The lineages of the Bourbon line is in dispute and rather confusing. The only way to sort it out is by more DNA examples that may, again, show that the line of decendents are not exactly how it seems.