::: The international study is included because it is about religiosity and intelligence, not religiosity and job preference. whether you agree that IQ is a good measure of intelligence or not, it is established in the literature as a measure for this purpose (with caveats). 
 ::: If you have cites showing that "the overwhelming majority agree that malnutrition, and cultural differences are the cause.", please add them. It would make that article a more accurate one. 
 ::: NAS members are far from a random selection of (US) highly intelligent people. A random selection of highly intelligent people would include people from many walks of life, many different jobs (including, I suspect, theologians).  It is OR to suggest otherwise, but this is the mistake commonly assumed when this  section is included. Consider this logic: 
 :::*Maybe many scientists were not invited to join the National Academy of Sciences, but since the invitation did not take into account the scientists' (gender /race/ sexuality/ etc), NAS contains a random sample of eminent scientists. 
 :::*Hence the section says that a lot of highly educated people aren't (female /black /gay /etc)! In fact since the (males/ whites/ gays) outnumber the (females/ blacks/ gays)..., it is clear that the vast majority of a random sample of highly educated people aren't (female /black/ gay). . 
 ::: clearly, not a logical path to follow. 
 :::(FWIW: According to http://csicop.org/si/2007-01/sagan.html, "Academy membership requires distinguished research scholarship, but that is rarely sufficient to ensure membership. Considerable weight is also given to public service, as well as more political factors such as where a nominee works and whom he or she knows." I am sure I have read this elsewhere as well.)