Alright, this is Sparrow's family. He had a sister, named Leopardpaw. She didn't make it past her apprenticeship, though. Both of his parents are dead. His mother is a Cornish Rex, I couldn't find a way to make her look like one, though. Height: 11 inches , being 9 lbs. His father is a Bengal cat, height: 14 inches, while being 12 lbs. Leopardpaw would've been 12 inches tall, 10 lbs if she survived. 

Sparrow(runner) is 15 inches tall, about 13 lbs. He didn't have the best relationship with his father, who always set high expectations on the tom. His mother and sister were all that mattered to him for some of his life, until things happened.