Karl Bonhoeffer (1868–1948) was a prominent psychiatrist/neurologist in Germany. Bonhoeffer opposed the ideas of Freud and Jung and, although initially in favour of sterilization programmes, it is said he refused to participate in the Nazi-sponsored sterilization programme started before World War II. Karl's wife Paula Bonhoeffer (1874–1951) was the daughter of a professor of theology and a German countess.
Karl and Paula Bonhoeffer had eight children, whom they educated at home:
- Karl Friedrich Bonhoeffer (1899–1957) worked as a chemist before and after serving in World War II and was married to Grete von Dohnanyi.
- Walter Bonhoeffer (1899–1918) was killed in action during World War I.
- Klaus Bonhoeffer (1901–1945) became a lawyer but served as a hospital orderly in World War I. He was executed by the Nazis. His wife was Emilie Delbrück, daughter of Hans Delbrück, and sister of Justus and Max Delbrück.
- Ursula Schleicher (1902–1983) married lawyer Rüdiger Schleicher (1895–1945), who was executed by the Nazis.
- Christel von Dohnanyi (1903–1965) married Hans von Dohnanyi (1902–1945), who was executed by the Nazis.
- Dietrich Bonhoeffer (1906–1945) became a Lutheran minister; he was engaged to be married to Maria von Wedemeyer (1924–1977) when he was executed by the Nazis.
- Sabine Leibholz (1906–1999) was the twin sister of Dietrich, and married legal scholar Gerhard Leibholz (1901–1982).
- Susanne Dress (1909–1991) married theologian Walter Dress (1904–1979).
Two sons of the Bonhoeffers and two sons-in-law were executed by the Nazis for their part in the German Resistance. In addition, Paula Bonhoeffer's brother, Paul von Hase, was also executed for a role in the Resistance, and the couple's daughter, Christel von Dohnanyi, and one grandson-in-law, Eberhard Bethge, were imprisoned by the Nazis but survived.
Dietrich, who joined the German resistance to fight against the evils of Nazi Germany, was arrested in 1943 and executed on April 9, 1945. Klaus joined the resistance and was arrested on October 1, 1944, with other conspirators, found guilty by the Volksgerichtshof and shot by the Gestapo on April 23, 1945.