The paradigm boa is not a double het. A double het is heterozygous for two gene pairs. The current best guess about the paradigm is that it has a Sharp albino gene paired with a caramel hypo gene. That is just one gene pair, making it a het instead of a double het. One member of a heterozygous gene pair must be a normal gene ONLY when there are a maximum of two alleles that can be plugged into the gene pair. When an allele list hits three or more, it is possible to make a heterozygous gene pair from two different mutant genes. It just happens that right now most allele lists for snakes contain only the normal allele and one mutant allele. More multiple allele situations will turn up as time goes by.

The more sensitive the test, the more likely that the tester is able to pick out the heterozygous individuals. "Dominant", "recessive", and "codominant" tend to be yes/no categories, while nature operates in shades of gray. When someone says he can pick out hets, I ask how reliable the test is and how easily can it be taught to someone else. If the instruction takes more than 10 minutes, and then the newly instructed person can't correctly identify 95% of the hets correctly, then I would not change the gene's classification to codominant.

Paul Hollander

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