11-year-old rapper MattyB teamed up with YouTube singer Olivia Kay to make a song for his sister, Sarah, who is living with Down syndrome. The song is aimed at people who look down on Sarah or bully her due to her developmental differences, and urges people to see each other’s “true colors.”

“Some people at school might pick on her for her needs,” MattyB, whose full name is Matt Morris, told ABC’s Good Morning America, “but I don’t think anybody should be bullied because of what they have.”

One in every 691 children born in the U.S. have Down syndrome, making it the most common genetic condition. Down syndrome is caused by an extra copy of chromosome 21 in the cell’s nucleus. This extra chromosome causes developmental issues and low muscle tone, smaller stature, eyes with an upward slant, and a single crease in the center of the palm. While some people with Down syndrome may have trouble learning and require specialized education, they can go on to live normal, fulfilling lives; some 20 percent of the Down syndrome population in the U.S. work paying jobs.

But MattyB hopes that his song will convey the message that his sister is just like anyone else aside from a few differences. “Sarah is just like any other normal kid,” he said. “She’s an awesome sister.”

Sarah, who is something of a YouTube celebrity herself, told GMA that “I can do baseball, or ballets or I like to dance. I do hip hop and I play soccer, and I do batting and I always play goalie.” She’s an active child, who has even rapped some of her brother’s songs.

MattyB and Sarah’s parents helped write the lyrics and produce the video, garnering some criticism that it’s all just to get a larger fan base. But whether or not MattyB is genuine in his new rap song, his message is clear and should be taken to heart:

I keep believing for the day we put our differences aside

And let a person be themselves before we cover our eyes

Imagine life without the boundaries we create with our pride

And opportunities we lose because we judge from inside