It's a similar story for physical strength. Nobody denies that men tend to be stronger than women, but most people vastly underestimate the disparity. In a study that measured grip strength in 2,000 people[2], the weakest 5% of men were comparable to the top decile of women. Even elite female athletes were only as strong as the median untrained male.
There are more examples (propensity for violence is another big one), but it takes time to find citations. Suffice it to say that most people think the sexes are more similar than they actually are.
1. https://brothersdiamond.files.wordpress.com/2015/02/menwoman... (For more on mental rotation and testosterone's effects, see my comment downthread: https://news.ycombinator.com/item?id=10443021)
2. http://egitim.judo.gov.tr/Dosyalar/makaleler/-ENG-Hand-grip-...