U...r...right!!!!! WHy didnt I see this before? That sooo makes sence!!!
Well, let see.....Snape, for some reasons, doesn't have family. Not wife and kids - I mean Fathers, Sister and so on.... ANd I know that Harry doesn't have anyone either, and probably many others dont have anyone too. But.....
But isn't it possible that Snape did have cousins and other relatives? Could it be possible that he killed them or brought them to Voldemort?
Also, may be ...Snape did not kill anyone directly. He is smart, very smart I think and may be he was like a strategist. Like he would make plans - Voldemort of course makes the most important decisions, but perhaps he would just tell Snape the goal sometimes, and Snape would find how to reach it. ANd tell others who to kill and so on.
I have a question - was Tom Riddle 1 generation older then Snape/James/So.on ? (i thought may be they have a longer history of working together then many other DEs..may be Snape was one of his earlier followers?)