I guess this about the large amount of research that has come out of things like https://ki.se/en/research/the-swedish-twin-registry https://ki.se/en/research/t

I guess this about the large amount of research that has come out of things like https://ki.se/en/research/the-swedish-twin-registry https://ki.se/en/research/the-swedish-twin-registry - hence the comment from a Swedish geneticist in the article. https://en.wikipedia.org/wiki/Swedish_Twin_Registry https://en.wikipedia.org/wiki/Swedish_Twin_Registry > The Swedish Twin Registry (abbreviated STR) is a twin registry based at the Karolinska Institutet in Stockholm, Sweden. Originally established in the 1960s, it is the largest twin registry in the world. It is widely used for medical research, with about thirty active research projects using data from the study as of 2019. As of 2012, it contained a total of 194,000 twins, 75,000 of whom were of a known zygosity. In principle, it contains records of every twin born in Sweden since 1886. Edit: A fascinating list of publications from ~2000 and onwards: https://ki.se/en/media/84204/download https://ki.se/en/media/84204/download (PDF, 1100+ records)