Like A Mother for Choco, Horace is a good book for young children.
Horace is a leopard being raised by tiger parents. The book starts off talking about his life with his parents- their house, the bedtime story he goes to sleep to every night, playing checkers with his Dad, his Mom making him slippers...and even the things he doesn't like, like eating oatmeal and brushing his teeth.
Then at his birthday party, when he was surrounded by his tiger relatives, he started wondering why he looked different from everyone else.
He tried drawing on himself to turn his spots into stripes. (The school-age kids I read this book to loved that part because it looks like he is doing a dot-to-dot picture on himself.) He cut pictures of leopards out of magazines and hung them up, and he even had a dream about being with animals that looked like him.
He decided to try and go out in the world and find animals like him. He found a family of leopards at a park and he had a great time playing with them, but then he got homesick. He realized that his family was not the group who looked like him, but the parents back at his house that he loved.
He left to go home and ran into his parents who were looking for him.
His Mom told him the same bedtime story she always tells him, but this time he stays awake through the whole things and hears: "We chose you when you were a tiny baby because you had lost your first family and needed a new one. We liked your spots, and we wanted you to be our child."
He then decides he wants to choose them too.
Horace is an adoption themed children's book that does not use the word adoption. It is geared towards young children. This book may be a good way to begin a discussion about differences in appearance between you and your child.