I like Genesis, don't care about the science in it.
I don't think that in any episode the concept of evolution has been used correctly. There is no path forwards or backwards, you cannot suddenly evolve or de-evolve.
Evolution goes in the direction that increases survival and reproduction odds at the time in the environment you're in. It's not some predetermined track.
But the biggest problem that all scifi is pretty much guilty of, changing your DNA does not instantly change you into how you would look like if you were born with that DNA. You'd just start producing the wrong proteins which would probably result in death.