What images, ideas, or perspectives does the book’s title suggest?

The most apparent, or accessible, answer to this question has to do with the title’s relationship to the old idea of color relationship to traditional, binary gender identification – blue for boys, pink for girls. The title, therefore, suggests that all boys are not like boys are expected or assumed to be. In his Afterword, the author adds two other possible interpretations, relating the color blue to the traditional color worn by uniformed police, and to the associations of violence and / masculinity that tend to be associated with that uniform. He also relates the color blue to the experience of being sad, or depressed. In both cases, the title evokes the idea that there are ways to be a boy that are not necessarily, or stereotypically, connected to masculinity and/or unhappiness.  

In the section of the book including the Author’s Note and Introduction, the author suggests that identification or claiming of gender identity is something that children should find out for themselves. How valid is this argument?