Terms
Homozygous = A visible mutation like Albino, Pied, Axanthic....(AKA Morph)

Heterozygous = that a snake is carrying a gene for a simple recessive trait.(AKA Het)

Alleles= a pair of genes that form a trait(one from each parent)

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    How do you get a Het?

In the following examples I am using pieds as the morph I am breeding for.

When a Homozygous snake ( Pied = pp ) is bred to a normal snake ( Normal = NN )........all the offspring produced will be normal looking AND "Het" for the Pied gene ( Het = Np ) You can only produce an entire clutch of offspring that are 100% het for a simple recessive trait if one of the parents is Homozygous for the trait.........meaning........it is visibly  a Piebald..........or an Axanthic.......or any other trait that is simple recessive.

• NN  = Normal Animal
• Np  = Heterozygous Animal (looks normal but has the lower case gene you want)
• pp  = Pied (2 lower case letters means it is a visible trait)

Top row represents one parent and the First column represents the other parent
Genes for any given simple recessive trait come in pairs (called alleles)
Babies get one gene from each parent

When a Heterozygous snake ( Pied = Np ) is bred to a Heterozygous snake ( Normal = Np )
Het x Het

	N	p
N	NN	Np
p	Np	pp

RESULTING OFFSPRING:

• 25% Normal = NN
• 50% Heterozygous = Np (look Normal)
• 25% Pied = pp

in four eggs.............1 baby will be normal ( NN = Normal )
2 babies will be normal looking and het for Pied ( Np = Heterozygous )
and 1 baby will be Pied ( pp = Pied "Homozygous" )

three of the babies will look totally normal
two of those three are HET
one of the three are normal ( not carrying the Pied gene )

The three normal looking snakes add up to 100% of the normal looking babies.
They each represent 33.3% of the total normal looking babies and one of the babies is "Normal" that normal baby makes up 33.3% of the total and the two hets together make up 66.6% of the total this is why when breeding HET X HET..........all the normal looking offspring are called 66% possible het.
You don't know which ones are the "true hets"(Np) all you know is that two out of three should be a HET............so that is where the 66% possible het comes into play.............odds are in your favor!!!.........Simply put..........in each baby snake.........you have a 66% chance that the baby is carrying the Pied gene.............and a 33% chance that it is not.
Currently there are no tests to show what genes a snake carries so you do not know if a possible het is a het until you breed it and produce visible morphs.
You do not always hit the odds in every clutch. You can have HET X HET breedings that produce no visible morphs (pieds) but over time it does average out to 1 in 4 babies being visible morphs

When a Heterozygous snake ( Pied = Np ) is bred to a normal snake ( Normal = NN )

Normal x Het

	N	N
N	NN	NN
p	Np	Np

RESULTING OFFSPRING:

• 50% Normal = NN
• 50% Heterozygous = Np (look Normal)
• 0% Pied = pp

When a Homozygous snake ( Pied = pp ) is bred to a normal snake ( Normal = NN )

 Pied x Normal

	N	N
p	Np	Np
p	Np	Np

RESULTING OFFSPRING:

• 0% Normal = NN
• 100% Heterozygous = Np (look Normal)
• 0% Pied = pp