Who is Ethan's family from A Dog's Purpose and what is their importance?

When we first meet Ethan, he is an eight-year-old boy. Toby, the main character, a dog experiencing many lifetimes, falls in love with Ethan immediately. Ethan returns that love, and the two become inseparable. In the end, and after numerous reincarnations, Toby comes back to Ethan as as Buddy , the black Labrador. Ethan recognizes him just before he closes his eyes for the last time.