 The sisters' fictional backstory was detailed in both Anthony Hayward's "The Who's Who of Soap Operas" and Josephine Monroe's "The Neighbours Programme Guide".It states that identical twins Caroline and Christina were born to an Australian mother and a second-generation Australian father, whose parents had emigrated from Italy.The have an older sister and two younger brothers, but the twins were always closer to each other than anyone else in the Alessi family.