I had never been particularly interested in the revolution until I saw the Anthony Andrews, Jane Seymour, Ian McKellen version of The Scarlet Pimpernel.The movie was fabulous, but it also fostered some interest into what happened to the Dauphin, the young Louis the XVII, who was held in the temple prison.
Geneticist's Latest Probe: The Heart of the Dauphin, explains that the heart of the boy who died was preserved by the doctor who carried out the autopsy. Although the preservation was not perfect-- the container in which the heart was kept had been smashed at least twice and the alcohol keeping the heart moist dissipated and the heart now resembles the consistency of a piece of wood-- scientists were able to take thin slices of the heart for genetic testing. The tests were sent to two, unaffiliated labs, one in Germany and one in Belgium. About six months later, the follow-up New York Times article reported that the labs conclusively determined that the heart belonged to a close relative of Marie Antoinette. So after more than 200 years, concrete evidence surfaced that the boy who died in prison was the Dauphin.