All that's actually known is that it was alleged, Beria apparently though it was credible and sought to suppress the rumor, and an anti-communist tabloid in the 90s claimed to have found someone claiming to be Stalin's illegitimate grandchild but no DNA testing was done nor was there ever any followup or further investigation. There's no hard evidence or even firsthand allegations, just reports that it was a rumor and that some people in the Soviet leadership believed it and that they may or may not have seen more direct evidence that was never recorded. Trying to find the truth of it is on par with trying to figure out who Jack the Ripper was or any other historical mystery: an exercise in futility given every witness and all physical evidence is long gone, at least unless the alleged descendant reemerges and DNA testing on them and Stalin's known relatives is done.
That said, I don't think the truth of the matter is ideologically important: the fact that Stalin was, as a person, kind of a piece of shit in general shouldn't be controversial. It's his role and performance as a leader and even the question of how much of that was specifically him as opposed to his bloc in general that are important, and even there he mostly only looks good in comparison to how royally his successors fucked up, along with being ascribed credit for the broader Soviet victory in WWII. That said, liberals constantly try to direct attention to Stalin in particular and frequently just repeat outright lies made up by Cold Warrior propagandists and if even an inch is given there they'll just double down and keep doing it even harder no matter how much one denounces him, because their goal isn't ideological discussion but to browbeat and silence any and every leftist (that's right, they do it just as hard to anarchists too because it isn't genuine, it's a rhetorical bullying technique), so it genuinely doesn't matter what Stalin did or did not do: he's not important anymore and truth doesn't matter to people who bring him up, so the only correct response is to ignore it and continue to emphasize the material successes of 20th century socialist projects instead of getting bogged down in relitigating what long dead men may or may not have done.
All that's actually known is that it was alleged, Beria apparently though it was credible and sought to suppress the rumor, and an anti-communist tabloid in the 90s claimed to have found someone claiming to be Stalin's illegitimate grandchild but no DNA testing was done nor was there ever any followup or further investigation. There's no hard evidence or even firsthand allegations, just reports that it was a rumor and that some people in the Soviet leadership believed it and that they may or may not have seen more direct evidence that was never recorded. Trying to find the truth of it is on par with trying to figure out who Jack the Ripper was or any other historical mystery: an exercise in futility given every witness and all physical evidence is long gone, at least unless the alleged descendant reemerges and DNA testing on them and Stalin's known relatives is done.
That said, I don't think the truth of the matter is ideologically important: the fact that Stalin was, as a person, kind of a piece of shit in general shouldn't be controversial. It's his role and performance as a leader and even the question of how much of that was specifically him as opposed to his bloc in general that are important, and even there he mostly only looks good in comparison to how royally his successors fucked up, along with being ascribed credit for the broader Soviet victory in WWII. That said, liberals constantly try to direct attention to Stalin in particular and frequently just repeat outright lies made up by Cold Warrior propagandists and if even an inch is given there they'll just double down and keep doing it even harder no matter how much one denounces him, because their goal isn't ideological discussion but to browbeat and silence any and every leftist (that's right, they do it just as hard to anarchists too because it isn't genuine, it's a rhetorical bullying technique), so it genuinely doesn't matter what Stalin did or did not do: he's not important anymore and truth doesn't matter to people who bring him up, so the only correct response is to ignore it and continue to emphasize the material successes of 20th century socialist projects instead of getting bogged down in relitigating what long dead men may or may not have done.