When Amanda Bowman Gray asked her daughter Lydia to watch her 25-month-old son so she could take a shower, she was taken by surprise upon her return.

Once Gray was finished in the bathroom, the mom of three stepped into the hallway and found her kids doing a duet of "You Are My Sunshine".

Want to know the most incredible part? Because Bo has Down syndrome, he only knows about 12 words - and "every word he has learned has been through music and singing."

Thanks to his sweet sister, however, he was able to pick up brand-new words from the song's lyrics.

In a video that Gray posted to Facebook earlier this week, Lydia can be seen strumming her guitar with her little brother by her side.

As they sing, the toddler gets especially excited when he says the words "happy," "gray," "dear," and "away". It's obvious that he can't help but light up as he shows off his new vocabulary.

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