Seven immediately occupying his rightful place

Or maybe momma cat had 9 kittens. Tiberius, Uhura, Troi, Riker, Spock, Geordie, Seven, Janeway, Bones.

Unfortunately I have to disappoint you. He is called Seven because he was born with a bend in his tail that resembles a “7”. I think he had 2 litter mates, and they went to different families.