There are systematic environmental differences for different cultures as well. This isn't to say "people aren't different", but rather that until you've estimat

There are systematic environmental differences for different cultures as well. This isn't to say "people aren't different", but rather that until you've estimated environmental differences and gene-environment interactions you know almost nothing about the nature vs. nurture debate. See http://cscs.umich.edu/~crshalizi/weblog/520.html http://cscs.umich.edu/~crshalizi/weblog/520.html for a great summary, including specifically questions about Jewish intelligence. I know it's a bit long, but I promise it's worth reading.