How effective are “early intervention” programs?

“I find myself caught between the genetics community – which takes it as a given that childhood experiences and education have a very limited role in shaping life outcomes – and the psychiatric community, which takes it as a given that childhood experiences and education are crucial in shaping life outcomes. Both sides have their favorite studies to cite supporting their positions. I’ve already talked about the genetics studies, so I thought I’d bring up a recent particularly good study from the other side.”