Mungojerrie and Rumpleteazer are Twins- and Macavity's son and 
daughter. When Macavity found out their mother was pregnant her tired 
to kill her. She escaped and managed to find the Jellicle Junkyard. 
She gave birth to Mungo and Rumple, and then died. Skimbleshanks and 
Jellylorum, who were barren of children at the time, adopted and 
raised them.

- Ozzie