Breeding really isn't the panacea you make it out to be.

I skipped grades, have an advanced science degree, earn a lot in a job that requires above average intelligence, etc. My parents were both high-school dropouts, and my mother in particular was identified as being "slow" when she was younger (not below average in IQ, but on the very low end of it). On the other hand, I personally know very intelligent couples (one consisting of a pair who each individually are far more intelligent than I am) whose kids have also been "slow".