Boys and girls are usually conditioned to fulfil quite different roles in the world. Parents generally raise boys to be autonomous, brave, and self-sufficient. We want them to stand on their own two feet and face the world as archetypal warriors.
By contrast, most girls are raised to have good relationship skills. Parents nurture girls to care, to share, to bond, and to be nice. This conditioning has an enormous unintended impact on the behaviour of boys and girls. Boys enjoy independence from a young age, and even fight for it, while girls often settle into looking out for that special relationship.
There are exceptions to these generalisations, but these are the ways in which we are all conditioned to nurture the roles of masculine and feminine children.