Once upon a time, Ganesh and Messua abandoned little four year old Nathoo because they weren't happy about his chances of survival. Once he had to be abandoned, he had to be kidnapped by Sharmila the tigress, the younger sister of Shere Khan.
Sharmila had to raise him reluctantly though, because she lost her cubs to various antagonistic forces including birds of prey. Years Later, she then had to kick him out of her den. So his rocky road to reuniting with his family had begun.