To determine whether there were differences between the sexes in the levels of DNA methylation, we examined the controls of each ethnicity stratified by sex. No point-wise significant difference of methylation level at any CpG site by sex was found in controls in any of the three ethnicities (African-American, Hispanic, or Caucasian). Assuming a significance level of 0.05 where the between-group variance is 1/10 of within-group variance, we had a 99, 95, and 99% power to detect a difference between sexes in African-Americans, Hispanics, and, Caucasians, respectively.
