What is the theme in The Summer of the Swans by Betsy Byars?

The Summer of the Swans contains the theme of growing up or coming of age in regards to the main character, Sara. Sara is at a rough age, caught halfway between childhood and adulthood. The whole world seems to be against Sara. Sara's body betrays her with its big feet, her ridiculously height and her poor, tortured hair. Sara's aunt oppresses her by forcing her to take her little brother everywhere she goes. Sara's own sister is another difficult matter because she is so beautiful it seems her mere presence makes a joke of Sara's own looks. Then there are the other children in town, the cruel ones who constantly make fun of Charlie and play cruel jokes on him, forcing Sara to come to his rescue time and time again. It seems nothing ever goes Sara's way.