I'm familiar with Murray's theories and they are frightening. But there are so many minorities who do accomplish wonderful things, it makes me think it is largely environment ... an environment we created with the Massa Great Society programs and others.
It is much more than theory; it is repeatable science. A bell curve has tails to both sides, accounting for the accomplishments you mention. You say "so many," but science says not so many. So do test scores, crime statistics, education accomplishments, earnings, costs to society, and inner city despair.
During most of history mankind labored with their bodies. Having a few very smart folks around was sufficient, and even very smart folks mostly did unskilled and low skilled tasks.
Over recent history unskilled and low skilled labor has been replaced by automation. The demand for such work has been filled by more reliable immigrants, first from Europe, China and Latin America. Guess who gets left out, when we encourage them to get a free college degree, but they can't do the work? We just dumb down the work, partly.
But while the education system goes along, the employers not so much. The encouragement of out of wedlock families has also contributed to a lawless culture. Drugs, alcohol, crime, prison, rinse and repeat.
Now the good news. The curve has tails to both sides; albeit centered one standard deviation to the left (at 85).
Murray's work has been largely substantiated by peer review, as well.