Doing the spider X spider breeding and following up with the offspring could help solve the long standing mystery of what type of mutation to classify spider.

The possibilities are:

1. Maybe spider is dominant and each egg from spider X spider would have a 1 in 4 chance of being a homozygous spider but would look just like their heterozygous spider parents. The test to find a homozygous spider among the regular heterozygous spiders in the offspring would be to grow them all up and breed to normals long enough to produce a long string of only spider offspring to prove a homozygous spider. If you none of the spider offspring prove homozygous spider maybe you just weren’t lucky enough to produce a one so you could start over with a new spider X spider paring. There have been rumors of a proven homozygous spider but no one has yet come out publicly to report being the person having a proven homozygous spider. Given the long time this mutation has been around (over 20 years) with no proven homozygous spider has lead me to start questioning the report that spider is dominant. But it still could be that just not enough people have done spider X spider breedings and then paid attention to what enough of the possible homozygous spider offspring produced to prove out a homozygous spider yet.

2. Maybe spider is co-dominant and either
A. The homozygous spider looks different and just hasn't been hit or shown publically yet.
B. The homozygous spider is different in that it either doesn't hatch, doesn't live, or doesn't breed, any of which would classify spider as co-dominant and homozygous lethal.

If 2B turns out to be the right classification for spider and the eggs never hatch it would be very hard to prove directly. We would just go on years and years with no proven homozygous spider which happens to be what we are seeing now. It would still be fine to breed spider X spider and all the heterozygous spider and normal for spider offspring would be fine, you just would have about 25% fewer good eggs or maybe 25% fewer thriving hatchlings if the homozygous spiders make it as far as hatching but not on to breeding.

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