http://precedings.nature.com/users/d96caf43c9b4dd11191cea188c12f7cf/ Documents posted by Bernard S Strauss Nature Publishing Group en Nature Precedings http://precedings.nature.com/images/header_logo.gif http://precedings.nature.com http://precedings.nature.com/documents/3238/version/1 The male female difference in the variance of quantitative traits including IQ can be accounted for by the observation of the concentration of genes involved in brain development on the X chromosome and by the mechanism of sex determination in mammals. Females have two X chromosomes with one randomly inactivated. Males have a single X chromosome, which results in increased variance. It is shown that these factors are sufficient to account for the observed differences. http://precedings.nature.com/documents/3238/version/1 Tue, 12 May 2009 10:56:39 UTC Why are Male IQ Scores More Variable? hdl:10101/npre.2009.3238.1 2009-05-12 Bernard Strauss Nature Precedings 2009-05-12T10:56:39Z Manuscript Genetics & Genomics http://creativecommons.org/licenses/by/3.0/