The book that SunofBeach is onto here is an excellent read. Its called "The Bell Curve" rather than jar [img]/images/graemlins/smile.gif[/img]

In that book the authors talk about all kinds of things that effect measures of general intellegence. Parents, schools etc. They say that to them it appears that if you have a large enough sample size then general intelligence is 60% genetic and 40% environmental factors. For any one individual it can be all one or the other factor though.
On the different types of intelligence most experts would say that there is a difference between verbal skills and mathematical skills. But many believe there is also a general intelligence factor for people.
When the authors commented on racial differences of general intelligence (ie Jewish race scoring higher, and certain minorities lower) that got some controversial press even though they also said that some of those differences could lessen over time.