Their population control problem was the the exodus ship can only fit a thousand people, but there and then at year 97, they had 2000 people living on the ark.
When the exodus ship did leave, all it had in there was 15 armed ####s who thought they were more important than taking enough breeding pairs to keep the species viable.
Of course that is an important reason for genetically modifying babies, by "safely" jumbling DNA with magic future science, that means that cousins can keep breeding with cousins, decade after decade without deformity. If they were genetically modifying foetuses, they could also genetically modify tolerance to solar radiation. The first generation of Astronauts up there may have been fine themselves, but when 1/2 their babies who came out were cucumber people. Steps had to have been taken.
You know when a teacher is teaching and they slowly start to say the answer to a problem, as the students figures out the end of the answer by hearing the beginning of the answer and race to say what the end of the answer is so that they seem bright?
That's what happened with Clarke and the President. She worked it out about 3 seconds before he told her, because the preceding 12 seconds of conversation was very clue ridden. In anyregard that she was prodded into developping that answer to why they are radiation resistant, this is something, wrong or right, that she a child did not know until that moment and was never anything any one ever told her on the Ark, or was part of the formal education on the ark that they were not human.
"That guy has ark blood in him" (massive paraphrase)
Ark blood is recognizably different to grounder blood and Mountainman Blood, probably because of the gmodding. So, yes, it seems pretty clear the first generation scientists up stairs in space were smart enough to invent new science that the (first generation) soldierboys and clerks in Mount Weather were not... And that the Mountain men and the Grounders can alike be upgraded. Probably not the existing generations, but their children should be able to live on the ground and be free of mutation. Mutation is still a grounder problem.