Th education of very young children like with Head Start is often criticized because when tested later the effects become smaller and smaller. So learning to read at 4 may help you in the first classes of primary school but when you are at high school your grades will not be much different from if you hadn't followed that program.
However, according to this article ("Occupy the classroom") there are other effects that are ore lasting: those children repeat less grades, are less likely to be diagnosed with a learning disability, or to suffer the kind of poor health associated with poverty. They are also more likely to graduate from high school and attend college.
Probably the attention of adults and learning to focus and learn are more important than what you actually learn at this young age. So mom teaching you to cook or dad teaching you to fish or track the traces of animals might be just as effective.