The evolution of the Genetic Thief is divided into five generations. The first generation hybrids look more like twisted, mutated, distorted monsters. Anyone with a normal mind (except its parents) would regard it as an unclean monster. The second generation hybrids look slightly more normal, but still do not resemble humans. Starting from the third generation, things change; they gradually become more human-like. As for the fourth generation Genetic Thieves, aside from slightly purplish skin, and patched bulges on the forehead, and baldness, they are indistinguishable from the host race.
The fifth generation Genetic Thief undergoes reversion, becoming a pure-blood Gene Stealer and starting a new cycle of infection.
