Nobel Laureate James J. Heckman, et al write,

Most economists are unaware of the evidence that certain personality traits are more malleable than cognitive ability over the life cycle and are more sensitive to investment by parents and to other sources of environmental influences at later ages than are cognitive traits. Social policy designed to remediate deficits in achievement can be effective by operating outside of purely cognitive channels.

This paper provides a lot to chew on. I recommend it highly. Thanks to Tyler Cowen for the pointer.