"Took my son to play piano for the seniors home in Pasadena," Musk tweeted. "It was lovely to see them smile."
Upon the request of a follower, Musk also included a 31-second clip of his son playing a classical piece on a grand piano.
Musk did not name the piece, but it appears to be "Deux Arabesques" by Claude Debussy, a French composer active around the end of the 19th century.
You can watch it here:
—Elon Musk (@elonmusk) October 27, 2019
Musk has five sons with his first wife, Justine. It's not clear which son was playing the piano, or how old he is. Musk is famously private about his personal life.
The billionaire — currently worth $22 billion — has made his philanthropic side known in the past. In 2012, he vowed to donate the majority of his wealth during his lifetime and has made many sizable donations to causes he cares about in past.
In 2014, Musk co-founded a small school named Ad Astra — Latin for "to the stars" — in Hawthorne, California, for his children. The school's curriculum includes artificial intelligence, ethics, and building things from weather-balloons to battle-bots.
Sports and music, however, are not included.