What does a "low IQ" have to do with manual labor? IQ or any other measure of so called intelligence, has never -- and will probably never -- have any correlation with a person's occupation. Ultimately, it is the parent's socio-economic status which usually dictates what jobs their children will have.
The fact that you believe it could be a person's "IQ" which dictates what job they may have really shows how little regard you have for people.
The fact that you believe it could be a person's "IQ" which dictates what job they may have really shows how little regard you have for people.