I think it started with Junie B. Jones, the star of a book series by Barbara Park. A person (who shall remain nameless to protect the guilty) gave my then four-year-old daughter a copy of Junie B. Jones and a Little Monkey Business, a story about a girl who was my daughter's age who was about to gain a new sibling, just as my child was at the time. Junie B. is brash and unstoppable, and is far from perfect, which I thought was a good thing for my daughter to see. My daughter greatly enjoyed the series, but after a few of the books, I began to absolutely HATE Junie B.