OSC REPLIES:
What an interesting parallel. There are differences, though -- for instance, Miriam could also be bitchy and judgmental, and I don't think Valentine does much of that in Ender's Game, and Peter was cruel and mean-spirited, while Aaron was merely fanatical in pursuit of his ambition to achieve a lofty goal. In a sense, the only real parallel is simply: Third child with an older brother and sister. That's the family Exodus gives us for Moses, but when I was novelizing Ender's Game (the short story has no family in it), I had no conscious thought of the Stone Tables character roster -- I simply drew on my own family as I saw it when I was seven or eight. Because, like Moses, I am also a third child with an older brother and sister. My older brother is not nasty like Peter, and my older sister is not perfect like Valentine -- but when I was seven I thought they were! So in giving Ender a family I lazily based his family situation on mine-as-a-child, and then exaggerated and extrapolated from there. In no sense is the fictional representation of Peter or Valentine meant to represent my real siblings -- I simply used my family as the starting point because ... well, why not?
That doesn't mean that I didn't also draw on some of the thinking I did in writing Stone Tables, since I created the play back in 1972 and didn't write the novel of Ender's Game until 1984. But if there was influence there, I had no conscious knowledge of it.