Complex sentence: The book became controversial after it was discovered that one passage of the book revealed that Dunham did acts of sexual assault to her sister when Lena was 7 years old and Grace was 1.
Split into simpler sentences: The book became controversial after it was discovered that one passage of the book revealed that Dunham did acts of sexual assault to her sister. Grace Dunham when Lena was 7 years old and Grace was 1.