The point in asking how one defines masculinity is to point out that there is no actual definition. Just the superficial traits assigned to us socially, and culturally within a given society. Basically that masculinity is a creation of man that we adhere to as a subconscious response to media, interactions with family/peers and education. There is nothing actual about masculinity, but the effects of toxic masculinity (which can result from those feeling they haven't lived up to their gender role) are very real, and very present all throughout our culture.
Women naturally look to men for leadership.
