Summer McKesson’s quest for answers to her medical condition would unearth a family secret – and a doctor’s decades-old deception that has ensnared multiple families across the country.

In 1812, hundreds of thousands of men in Napoleon's army perished during their retreat from Russia. Researchers now believe a couple of unexpected pathogens may have helped hasten the soldiers' demise.

Once an antibody latches on to a pathogen, broadly neutralizing antibodies inactivate it (as their name implies). This is typically because these antibodies bind to a site that’s necessary for a protein’s function. For example, broadly neutralizing antibodies to HIV bind to the proteins that help this virus enter immune cells.

Your pet is your best friend, but how well do you really know them? By giving the gift of Embark’s dog DNA tests or investing in one for your own family, you’ll get to know your right-hand man, your four-legged lady or your paw-some pal on a cellular level.

Owner Katie told Newsweek she thought she was adopting "a Saluki mix," but Faris's DNA test showed a far more varied genetic makeup.

At least two traces of DNA have been found in the investigation into the shocking heist at the Louvre Museum in Paris, authorities confirmed Thursday. The DNA samples were taken from a glove and a helmet left behind by the robbers, investigators told ABC News. They have not yet been matched to any suspects.

Robert Koehler, 66, is facing new charges in a case that dates to 1984. He is accused of breaking into a townhome in Miami-Dade and kidnapping and sexually assaulting a woman. Miami-Dade sheriff's deputies recently solved the case after linking Koehler's DNA to the victim, who is not identified in court records.

A major development in the manhunt to find the four people who robbed the Louvre Museum in Paris has been revealed. According to French police, two traces of DNA were found in one of the helmets and one of the gloves the suspects left behind at the scene of the crime.