The most pedestrian explanation for sex-based heritability differences for PTSD is that reliability and/or validity of PTSD diagnosis differs by sex. Lower male heritability could be a result of lower reliability and validity of PTSD diagnosis in males, because heritability estimates are always capped by reliability and validity of measurement. Regarding this possibility, it would be worthwhile to examine reasons why particular populations might systematically over- or under-report PTSD (thereby decreasing reliability and validity). Perhaps cultural factors that are more permissive for accurate reporting of PTSD symptoms in females contribute to more precise measurement of PTSD in females, and this would permit higher heritability estimates. The same issue of reliability and validity applies if diagnostic nosology is more appropriate for females than males. If the current PTSD diagnosis ‘carves nature at it’s joints’ better for females than males, there will be a lower bound on male heritability estimates compared with females.
