Question about pied markings

I have a question about the markings on pieds. What is it that makes the borders of the saddles on some snakes smooth and colored like this?:

http://www.morphmarket.com/c/reptile...-pythons/33294

And on other snakes dark and pixelated like this?:

http://www.morphmarket.com/c/reptile...-pythons/43530

Do the smoothies become pixelated with age? Is it genetic? Random happenstance?

Good question. I wish I knew the answer.


My boy has pixelated borders and has since he was 190g, so I'm pretty sure he's had them since birth and I doubt they'll change. So far I'm chalking it up to random happenstance, but I suppose that if my breeding attempts are sucessful I'll find out whether or not it's genetic.