The purpose is to give an explanation of her origin and true roots to her English language today. Also she makes a good point that just because a person is not necessarily good at a certain thing but has a passion for it, does not mean you have to give the passion up and settle for what you are good for. In other words, do not rely on peoples opinions.
Opinions are merely thoughts and nothing more.
The story inspires me to persevere and press toward my goal in life. I know that the odds are against me, but I know that I too can be successful as Tan. Well I have grown up in a minority family. Both my parents have a very good vocabulary and speak English very well. My grandparents are Mexican and speak English well but broken to a certain extent.