The Utah mom posted a now-viral touching and tear-jerking video of her daughter, Lydia, strumming on her guitar and singing "You are my sunshine," to her baby brother, Bo, who has Down Syndrome.

Lydia, wearing a pink sweatshirt, has her back against the hallway floor, and Bo, in red pajamas, rocks back and forth, looking adoringly at his older sister. It's obvious the two have sung together. Lydia pauses on key words, such as "happy" and "dear," allowing her brother to try and sound out the words himself.

Gray posted the video on Monday as proof that music therapy does wonders. She said Bo, who is 2 years old, only knows 12 words, but that all of them have been learned through "music and singing."

Gray and her husband are both musicians.

Credits: Amanda Bowman Gray