Hox Gene is a DNA sequence found within genes that are involved in the regulation of development (morphogenesis) of animals, fungi and plants. Genes that have a homeobox are called homeobox genes and form the homeobox gene family.
Mutations to homeobox genes can produce easily visible phenotypic changes.
Hox genes formed the basis of Professor Cthulhu's genetics lecture. He explained how genetics determined appearance and ability to his class. He also explained that a series of mutations in a distant ancestor during the Cambrian period made it possible for sentient mollusk life by duplicating the normal eight to ten Hox genes into four clusters of up to thirteen genes each.
After class, Nyarlathotep asked the professor whether chance could have given rise to a non-mollusk sentient life form, perhaps based on amphioxus. Professor Cthulhu found the idea laughable.
The Snarre't had learned thousands of years ago how to develop devices that could tamper with hox genes. These "hoxbombs" scrambled the sequence of hox genes and added genes in places where they didn't belong. They were actually quite easy to build and deploy. It wasn't long after contact between the Snarre't and humans that both species learned that hoxbombs could also impact humans.