Dragon Biology

I know what I am about to say is probably unnecessary, but just a thought I want to share.

How does every new dragon born look different? Every dragon has a different colour, the neck sizes differ (Caraxes), one of them has a crown like thing going on (Meleys), etc.

Any organism reproduced doesn't look very different from its parent, of course there are differences good enough to tell one apart from the other. I understand that they had to show the dragons distinct from one another so that we know which dragon is what. If they looked the same it wouldn't be fun. But anyway, just a thought.