Good question.



"Het" is slang for "heterozygous", which refers to both a gene pair and the creature possessing that gene pair. Genes come in pairs, and a gene pair that is heterozygous is made up of two different genes. Usually, in a heterozygous gene pair, the two genes are a normal gene and a mutant (abnormal) gene.



"100% het for piebald" means that it is certain the snake has a piebald mutant gene paired with a normal gene. Usually it is certain because one parent was piebald, though it might be certain because of a breeding test. Het piebald snakes look normal when they are born and do not change; they look normal on the day they die.



When a heterozygous animal looks normal, the mutant gene is classified as a recessive mutant gene. When a heterozygous animal does not look normal, the mutant gene is classified as some sort of a dominant mutant gene. So piebald is a recessive mutant gene.



Piebald ball pythons have two copies of the piebald mutant gene in their gene pair. They are born piebald, and the piebald pattern does not change during life, though different piebald snakes have somewhat different amounts and distribution of white.



The value of het piebalds is in mating two of them. When that is done, the breeder expects 25% of the babies to be piebald, though the actual percentage may be a bit over or under 25%.



Hope this helps.



Paul Hollander

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