I don't actually know that much about Stalin as a person, but from what I've heard I don't think he was really that into family or carrying on his line, especially not after the suicide of his second wife (or maybe he killed her himself). Stalin's first wife died in 1907 of illness and apparently this messed him up pretty badly. So perhaps if she does not die, or if they never marry and therefore Stalin falls in love with another woman later on with whom the relationship is a lasting one, then he might feel more obligated to care for whatever children he has, and perhaps set them up to be heirs.