[quote=Tyki]
it's only not instant because he has to think it up and test it repeatedly until he gets it right... the zerg strain i have is capable of doing that at a much sped up rate and then apply it to them selves without killing themselves
[/quote]

Mutations in the DNA only take effect after rebirth, meaning their kids would have it. Furthermore, the mutations are very greatly limited in scale, and require something called Essence. Lastly, each test would require you to spawn a new generation of Zerg, as only then the mutation takes effect.