50% het?

[OhhWatALoser]

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?

parent one has one recessive allele and one normal allele
parent two has one recessive allele and one normal allele
egg #1 has 4 possibilities
1. to receive both recessive alleles
2. to receive recessive allele from parent one and normal allele from parent two
3. to receive normal allele from parent one and recessive allele from parent two
4. both normal alleles

If the egg gets both recessive alleles it is easily identified.
If the egg gets only 1 recessive allele or both normal alleles, they cannot be distinguished form each other.
you have 3 options
1. to receive recessive allele from parent one and normal allele from parent two
2. to receive normal allele from parent one and recessive allele from parent two
3. both normal alleles

so the chance of the egg getting a recessive allele is 2/3 or 66%
repeat the above for each other egg in the clutch.