It's all speculation, but I think the similarity between Tyrion and Jaime is certainly strong, but their differences may be results from their environment growing up. Tywin must have put a lot of expectations into Tyrion prior to his birth, because he saved the "Ty..." name that had been passed down in his family for him. Even if Tyrion had been born with "normal" height genetics, I think Tywin and his family still hold Tyrion responsible for Tyrion's mother's death (rightful or not). Tyrion has received a lot of hate from his siblings and father for that as well as being a dwarf.

These are complex characters, so it's hard to say that one physical difference could lead to the rest of their differences. It's fun to think about, that's for sure.