Fiona, I was actually just thinking about this today. DD is only 5 months old and her little personality is just starting to shine. Where DS was more quiet, serious and liked to be left alone, on the floor, to watch the action from afar; DD is more social and giggly, and thrives on cuddles, and is so tactile- she wants to touch everyone, and snuggle in. It's fascinating to see how different they are.