Complex sentence: Adelaide was the second youngest of her parents' seven children, and she and her sisters spent most of their childhood and adolescence in England, where her father had retired in 1872 with his family on a pension of 666 pounds sterling.
Split into simpler sentences: Adelaide was the second youngest of her parents' seven children. She and her sisters grew up mostly in England, where her father had retired in 1872 with his family on a pension of 666 pounds sterling.