I have to laugh at the notion that those abilities aren't very malleable. Does Murray actually believe the best athletes and musicians weren't nurtured in their abilities? The truth is, it's all about nurture, including linguistic and logical-mathematical ability. However, the nurture required cannot be given by the government; it comes from a stable family where children are encouraged to excel.
No, it's not ALL about nurture. A stable family and good schools will not enable every child to master calculus. Many kids are just not smart enough. Even siblings who share the same home environment and go to the same schools can differ drastically in academic achievement. Here is a personal example. I am a very good chess player and a terrible baseball player. My hand-eye coordination is simply bad, and no amount of parental support would have made me a good ballplayer. Parental support (taking me to chess tournaments, buying me books) did help me become a chess master.