Ok, that's a big question. But there was a column in the editorial section of the Tulsa World this morning (Nov. 19, 2014) by Charles Murray titled "Parents lose credit for children's IQ". He reports on 2 different studies, one by Kevin Beaver of Florida State University. He could find little evidence to indicate that a child's home life had any significant effect on the child's IQ. That doesn't say that there is none. The other study was by 6 authors from King's College, London. They applied Genome-wide Complex Trait Analysis to determine how much a child's IQ depends on genetics and how much on environment. According to their analysis a child's IQ does not have much to do with their family life. There are effects that depend on the environment in some complex way, but it is not dependent on the family for development. If a child is deprived in some way then that may affect his IQ, but it isn't clear how a child living a normal life will be affected.
The lesson we are supposed to come to from these studies is that we should love and support our children and let them develop as they will. There doesn't seem to be much we can actually do to help them develop a higher IQ.
One caveat,Charles Murray is the author of "The Bell Curve", 1994. This is the book where he claimed there are significant differences in intelligence between the races, and whites are at the top of the heap.
Bill Gill
