50% het?

[CH2O2]

If you breed het x het each normal looking hatchling will have a 66% of being a het and a 33% chance of being a normal. It doesn't matter if there is one normal looking hatchling or four normal looking hatchlings each one has a 66% chance of carrying the recessive gene.

I don't understand how that can be. Can you show me the mathematical calculation you make to arrive at the number 66%? I understand that would be the case if you have 3 normal looking snakes and 2 of them are het. 2 out of 3 is 66%. But how do you arrive at 66% when you have a clutch of 4 normal looking snakes from a het x het?