So to me it seems like arms and legs are pretty similar that they almost have the same blueprint. And if you change part of it like the number of digits, you will have 12 fingers and 12 toes.
But at the same time there are differences.
So my question is, are arms and legs encoded with the same piece of DNA? Or two very similar pieces. But in that case why would a change in the arm blueprint to give you 12 fingers also give you 12 toes?
On the other hand if arms and legs are encoded by the same piece of DNA. How do legs develop heals and arms develop wrists?
Are arms and legs only different by their shape (morphology?).
Equally if a thumb is encoded by the same DNA as encodes fingers, (i.e. all are similar and have fingernails), why are thumbs different?