"Enviroment difference in how children are raised play a significant role in intelligence" (IQ-Genetics or Enviroment, Fabian Grasso, July 22, 2002, allpysch.com/journal/iq.html) "Depriving children of a loving family environment causes lasting damgage to their intelligence. The studies showed that children in the most deprived conditions had exceptionally low IQs, but once they were removed from from those conditions improved when tested again at 42 and 54 months." (A loving family can boost childrens' intelligence, Ian Sample, February 18, 2006, guardian.co.uk) This correlation does not mean a conclusion. Environment does have an impact on intelligence, but this is not the only factor.