So… Chris’ video is not entirely correct. I give him credit for trying to explain but he just does not have the right information.
To explain, let me go all the way back to the start. “Paradox” is an ■■■■■■■ term used in the reptile industry/hobby that has no scientific/genetic value. It simply describes an anomalous phenotype, anywhere from a small, nearly undetectable colour/pattern difference all the way up to these extreme 50/50 animals.
The two most common forms of “paradox” that we encounter in the hobby are Mosaics and Chimeras
A mosaic is an animal that has genetically distinct cell lines but they originated from a single zygote.
A chimera is an animal that has genetically distinct cell lines but they originated from more than one zygote/individual
Now… What does that mean? I hear you asking
You breed an Albino to a WT and what you hatch are het Albinos. But one of them has random full Albino patches on it. This happens because, for reasons (I know a number of reasons but I am trying to keep @thecrawdfather’s brain from imploding), the wild-type allele of the gene is lost in a subset of the cells in this animal’s body. So the animals then has two genetically different sets of cells in its body - 2n and 2n-1 - but all of the cells in its body have the same embryo as their origin. This type of “paradox” animal is a mosaic
You breed an Pin to a WT and what you hatch are Pins and WTs. But one of the Pins has random WT patches on it. This happens because, most often, two different fertilized ovum fuse to create a single embryo. This give you an animal with two genetically different sets of cells in its body - 2nw and 2np - that each had an independent origin. This type of “paradox” animal is a chimera.
Make sense?
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Now, these bilateral animals are almost assuredly simple mosaics. The first division of the fertilized embryo sets up the left/right asymmetry, so if the chromosomal non-disjunction event happens there then every cell on one side of the animal will have lack one of the alleles while every cell on the other side of the body will have both of the alleles.
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This is unlikely to happen. The simple version is that fusion of the two embryos occurs when one essentially engulfs the other. In an easily visualized analogy, one becomes the hotdog and the other becomes the bun. The hotdog then goes on to make most of the internal organs, and the bun becomes the skin and digestive tract. As such, both of the gonads would be made of hotdog.
