Some people are calling bullshit. According to a report by a Russian mathematician, Calment was not the nigh-immortal she claimed to be. In some straight up Days Of Our Lives shit, the theory goes that the woman who claimed the record was in fact Calment's daughter, Yvonne, who had assumed her mother's identity. Why? To avoid paying inheritance taxes, of course.
Statistically speaking, Calment's lifespan does seem next to impossible. Also, Yvonne's alleged deception would have happened decades ago, in a small French town, before the internet or DNA testing was widely used for identification. So this certainly has all the makings of some malarkey ...
So Is It Bullshit?
It might seem like a wrinkly ol' fib if you ignore the vast majority of evidence and every single peer-reviewed study on Calment. Supercentarians (people 110+) are pretty damn rare, so much so that when researchers get the chance to study one, they go hard. Calment was questioned at length about the minutia of her life, which was then corroborated with a whole slew of official documents.
There's also the sheer logistics of it. For such a deception to have worked, Calment's whole 50,000-person town of Arles would have had to go along with it. Also, the accusations cite a Facebook poll in which a Russian doctor asked his followers to rate how old Calment looked in a photo. In terms of scientific rigor, it's like calculating the distance to Mars by asking people on your morning subway ride for their best guess.
These theories of Calment as an impostor have been around since at least 2000. The only reason it's caused such a hullabaloo now is that there are websites such as ResearchGate, which allow just about anyone to upload a "scientific" report without having to go through pesky hurdles like actually being scientific. The accusation has also been widely dismissed, and even accused of being an elaborate part of a Russian misinformation scheme, which is honestly the least surprising aspect of it.