Previous research has shown females with a male twin to be more proficient at mental 3d-spatial tasks. As that paper explains in its introduction, this is "pro

Previous research has shown females with a male twin to be more proficient at mental 3d-spatial tasks. As that paper explains in its introduction, this is "probably the most robust cognitive sex difference", emphasis mine, which is why it's interesting. https://www.ncbi.nlm.nih.gov/pmc/articles/PMC4438761/ https://www.ncbi.nlm.nih.gov/pmc/articles/PMC4438761/