Anyone who played Hogwarts Legacy knows the character Ominis Gaunt, he is obviously a relative of Voldemort, according to period calculations and even from things he says in the game about his older brothers, we can assume that Ominis is a great-uncle of Voldemort, being one of his cruel older brothers, Marvolo Gaunt. Now, the question remains, was Voldemort the only heir of Slytherin? Assuming that Ominis had children and a bloodline, today there must be a huge family descended from Slytherin, but that people don't know about, as the name "Gaunt" may have been swallowed with time, but they're still all Parselmouths and all.