Yo-Yo Ma's wife, First Lady, or Beyonce?

We watched the Kennedy Center Honors on TV where Yo-Yo Ma, the famous cellist was being honored. Next to him was Michelle Obama. My mom said, "Is that his wife?" My husband said, "Emilie, don't you know the First Lady?" Olivia, our 5 year-old said, "No it's not, it's Beyonce!"