I think you should update your reference baseline. Start with looking for papers who cite those papers, see what they think and what they found. For one, with

I think you should update your reference baseline. Start with looking for papers who cite those papers, see what they think and what they found. For one, with recent advances in genomics, we now realise that conclusions from twin studies in general aren't aging so well. And all the above don't really do genetics, they used seemingly close-knitted cohorts. In themselves I find all the papers you pointed dubious at best, and more likely garbage. The experimental setups in all of these were rather weak to start with, and did not allow to discriminate between causation and correlation, and the authors all achieved/generalized conclusions that were not supported by their own data. Our societies fascination and obstination with deriving things from IQ is, well, fascinating... No of these start with asking a question to understand a tractable and useful problem. They're all a my "d!ck is bigger than your d!ck" kind of ranking problem.