Niels Bohr was the second of three children in his family.
He was born in Copenhagen on 7 October 1885 to Christian Bohr, a professor of physiology, and Ellen Adler Bohr. His older sister was Jenny, and his younger brother was Harald, making Niels the middle child of the family. Harald later became a distinguished mathematician and an international footballer.
The Bohr household encouraged both intellectual discussion and wide-ranging interests. Christian Bohr’s scientific career brought researchers into the family’s circle, while Ellen came from a prominent Danish Jewish banking family. Niels and Harald shared a passion for football as well as mathematics and science; both played for Akademisk Boldklub.
This fact concerns Niels’s birth family, not his own later household. Niels and his wife, Margrethe, had six sons, including Aage Bohr, who became a physicist and won the Nobel Prize in Physics in 1975. That later family size is a common source of confusion when reading summaries of Bohr’s life.