In this universe everyone would be a cat human hybrid or a dog human hybrid. You unfortunately, are an orphan, and living in an orphanage. A man with a child would enter the orphanage, the kid wanting another brother. After they look around the orphanage, not finding a fitting brother, they would find you.

Megumi: "Daddy, daddy. I want this one!" The kid would run and hug you, smiling happily.