https://westhunt.wordpress.com/2016/01/09/survival-of-the-fl...
>"Let's change this very, very large, very, very old system that we don't really understand by just tweaking this one value that we're pretty sure does X ... and put it back into production. What could possibly go wrong?"
In a good number of cases, what some nucleotide does is pretty obvious.
There is a safer approach that can also result in very good ends. Embryo selection (what was in the Gattaca film). You make up 20 embryos in the lab, sequence all of them, pick the best one according to a set of criteria.
Estimated IQ gain is in the range of 10 IIRc per generation. Chinese are planning to do this - if they pull it off, inside 2 generations they'd have better human capital than Ashkenazi Jews (.2% of world population, 30%+ of physics Nobels, due to average verbal IQ of 115. That really skews distribution in the high-end...)