You can tell by the way they part their hair.
Also, he doesn't have to part his hair any more.
I parted my hair a certain way, to look younger.
He tried to part his blond hair on the side, but it refused.
I doubted that he could successfully part my hair with it.
He parted his hair a little more towards the centre.
At once he parted her hair and started to braid it.
Once upon a time it had seemed to Ralph she saw everything, even a change of half an inch in where he parted his hair.
One child, a boy with neatly parted hair, looks carefully around the room to make sure that nobody can see him.
He felt a whfffff as the ball nearly parted his hair.
Idiome