He fathered 20 children

In the 18th century, it was common for relatives to get married. Bach's first wife was his cousin Maria Barbara, to whom he was married. She did not need to change her last name because they were connected. Through their fathers, they were first cousins. When Sebastian was 35, Maria died. Together, the couple had seven children, but only four of them survived to adulthood. Maria was reportedly not as interested in music as he was, despite coming from a family of musicians. This is possibly one of the reasons Bach composed so little music at the time.

Six of the thirteen children born to Anna Magdalena, Bach's second wife, survived. Anna was a vocalist and musician in addition to transcribing many of Bach's compositions. She was the subject of several compositions by Bach, notably "The Notebook for Anna Magdalena Bach."

Of his offspring, Wilhelm Friedemann, Carl Philipp Emanuel, Johann Christoph Friedrich, and Johann Christian all followed in their father's footsteps and pursued careers as composers and musicians. His other children reportedly grew to love their father's music later in life and frequently included it in their performances.