The two dolls I have so far is a couple. I was lucky that the height difference between them is about the same as their original characters (got my first two dolls as gifts). I would feel that it was weird if the height difference was any bigger since their height is relevant to their characters. But it would also feel strange if one had been more mature than the other. If this had been the case I would probably look for another doll I felt is more right for the character.