The source of self-esteem in normal boys is based in action. The source of self-esteem in girls is based in the estimation of others. From their first abilities to read the perceptions of others, girls begin to realize that they are positively or negatively judged based on appearance, size, weight, skin color, grade of hair and a host of physical and social attributes over which they have no control.
When children begin to mimic the behavior of their parents, they are judged on their actions, not as carbon copies of people who may be in the same room, engaging in the exact same behavior. The attention demanding, obnoxious child who constantly yells, "Look at me! See what I can do!" does not pick that behavior out of thin air. She is mimicking someone's behavior.
As girls begin to interact with others in school, the comparisons are merciless. Someone else is poorer, richer, prettier, thinner, fatter, smarter or just different. With boys, the ones who can mix it up in play, hold a decent conversation about sports, or engage in other action based activities find it easier than girls to fit in.
Self-esteem issues become problematic when the child attempts to improve appearance by asking for better clothes or tries to style her hair like the "prettier" girls. In many cases, neither the hair nor the financial situation at home will cooperate.
When dysfunction in the home allows for constant criticism, abuse, or intolerance, even the prettiest and most well provided-for girls will become unable to see themselves in a positive light. Such home environments stifle the girl's ability to develop social and interpersonal skills or will lead to problematic behavior.
When problematic behavior generates enough satisfaction or reward as a way of improving self-esteem, the negative external inputs begin to pile on, and the child receives more confirmation of inferiority, but now the negative judgments are based behavior that is the child's responsibility.
As girls progress through life, self-esteem issues can end life early, destroy life permanently, or be resolved into forms of denial or protective self-assessment. It is always said that the "cool girls" simply did not care what people thought of them and fiercely protected themselves from anyone who tried to get pushy about making negative judgments.
Now, women who would be shamed for being 100 pounds overweight get on through their lives and careers. Cosmetic surgery is available to correct just about any flaw or deformity. Psychological counseling is available for treatment of self-esteem issues. Spiritual programs allow for acceptance of self and one's own value in the world.
Some of the ugliest actresses on record are getting top roles on television and in film. Some beautiful actresses have won Oscars while looking as awful as they could. Weight is no longer the giant brick wall that prevents women from becoming top runway and photographic models.
Women can be incredibly smart and show it. Women no longer have limited ability to get food, clothing, shelter, and independent income on their own. Women can learn trades and skills that were previously closed to them, allowing them to follow their passions instead of doing what the world allows them to do.
Best of all, the concept of "acceptable" roles for women need not be controlled by others or limited to traditional roles of parent, homemaker, and followers of men.
But the final wash over all of the advancements in allowing women to develop their self-esteem, is in their upbringing and pasts. Some self-esteem issues, based in family dysfunction, are not easily overcome.