>some of heritability is genetics and some is the shared environment.

This is not the definition of heritability you are mincing words.

Heres the definition of heritability:

(HAYR-ih-tuh-BIH-lih-tee) The proportion of variation in a population trait that can be attributed to inherited GENETIC factors.

>For example, someone is quite likely to speak the same first language as their parents, and for this reason, the statistics for heritability come up with a high number for how heritable a trait first language is.

you are conflating inheritability with heritability.

The reason we are able to have crops that yield more is because we genetically modified them to do so; not because we grew wild corn in the perfect environment.