"Gender-based behavior is largely socialized behavior and has little to do with biological sex, but a lot to do with how we think those of our own gender should act. It is the first part of the social self learned, and at a time when our judgment is least critical, making such behavioral choices a stable part of your personality by as early as the third year. Gender identification is learned personality and part of the structure of the social self and ego. It's part of what gets killed on the warrior path."
—Dr. Glenn J. Morris, PhD., ScD., Kudan (9th dan) Bujinkan Budo Taijutsu, Rokudan (6th dan) Nihon Karate Jujutsu. Author of Path Notes of an American Ninja Master, one of my favorite books read in 2015.