I have DS identical twins, 14 months.
One twin is felt handed, the other right handed.
The one who is right handed got his first front teeth on the right.
The one who is left handed got his first front teeth on the left.
One has a dimple on his left cheek, the other on the right.
Oooh it all feels very science fictiony and interesting.
Methinks I'll do a PHD on it :)