Which is why we need to fully sequence the human genome so we know what has been mutated in the first place so we can fix it, and yes, the first humans who colonize space will run into deadly problems, just like how people who sailed to america knew they might never find anything and die too.
I would personally agree to be one of the first humans to colonize mars even if it was a one-way trip with a 99% chance of death within a few short years, atleast my life would helped propel the human species forward in a huge way