This is a tough one.

I don't know a whole lot about the scientific research regarding whether or not intelligent parents produce intelligent children, but I do have some real world knowledge.

I often see that children who have two intelligent, successful parents often turn out to be successful themselves. In many instances, they surpass their parents level of success.

I guess the question comes down to whether or not the child was predisposed to success based on the inheritance of one or both parents genes, or whether it was their upbringing. Intelligent, successful parents often have high standards which they expect their children to adhere to. I've seen this work one of two ways. The child will comply and fulfill and/or exceed their parents expectations, or they will rebel and completely fall short of the mark, often ending up as complete failures in the eyes of their parents.

This phenomena leads me to believe that IQ is in fact an effect of the person's upbringing more so than genetics.