But with each passing year and each new study, the evidence for the genetic contribution to these [individual and group] differences becomes more firmly established than ever.
Mankind Quarterly, Volume 39, Issue 2 (p. 231), Winter 1998.
![But with each passing year and each new study, the evidence for the genetic contribution to these [individual and group] differences becomes more firmly established than ever.](http://cdn.quoteddaily.com/images/j-philippe-rushton/but-with-each-passing-year-and-each-new-study-the-evidence-for-the-genetic-contribution-to-these-individual-and-group.jpg)