Even if Tom Riddle hadn't left Merope, that doesn't guarantee it would necessarily be a loving home. Plus this gets into the whole nurture vs nature thing. It's true that Voldemort never knew love and that was part of the reason why he became as evil as he did, but even growing up with both his parents, he still could have the capacity to do many of the things he did, though maybe not quite to the same extent.

Chelsea//Ravenclaw