The results showed that both boys and girls were able to crawl the same degree of incline. However, the predictions of the mothers were correct within one degree for the boys and underestimated their daughter’s ability by nine degrees.
What this shows is that the presumption that boys are more physical causes parents to encourage their boys more in physical activities while cautioning their girls. This further translates into providing more opportunities for boys to be physical and fewer for girls. The result?
Boys actually do develop stronger physical skills than girls. But not because of anything innate or biological, but rather because of the gender roles that the parents subconsciously projected onto their babies."
The experiment mentioned is available in full HERE.