It's not true. No high-quality study, some of which go much higher than MENSA level, corroborates anything remotely like what they claim from their doubly-selec

It's not true. No high-quality study, some of which go much higher than MENSA level, corroborates anything remotely like what they claim from their doubly-selected MENSA respondents self-reports: https://www.gwern.net/SMPY#fn1 https://www.gwern.net/SMPY#fn1 For example, http://programme.exordo.com/isir2017/delegates/presentation/35/ http://programme.exordo.com/isir2017/delegates/presentation/... looks at health in SMPY participants, which are a full SD or so above Mensans. If OP were true, they would have odds ratios of scores or hundreds (or higher!) compared to normal people of serious psychopathology, and SMPY surveys would be a staggering wasteland of mental illness; instead, they are very healthy and have rates lower or just slightly above normal people. Or even more recently, "Can You Ever Be Too Smart for Your Own Good? Comparing Linear and Nonlinear Effects of Cognitive Ability on Life Outcomes" https://www.gwern.net/docs/iq/2021-brown.pdf https://www.gwern.net/docs/iq/2021-brown.pdf , Brown et al 2021, finds absolutely no evidence of any quadratic trend remotely like OP claims.