Visually of course. I've always been informed to look for marble/shattered pattern where the belly color meets the colors on the snakes sides.

Is there a head stamp to look for?

My Banana Enchi Yellowbelly is posted below. Is there anyway to determine this without knowing the parents?

https://imgur.com/a/oR7lZNy

https://imgur.com/a/ZPRLXrd