They raised eight children in the Mansion. Their oldest child, Mary, learned the zinc business at an early age, often helping her father at the plant. She continued this interest by being the first woman to graduate in engineering from the University of Michigan. She also was the first woman to graduate from the School of Mines in Freiberg, Germany. When Paul Carus came to work for her father at Open Court Publishing, he and Mary fell in love and married in 1888.
Mary and Paul Carus had six children who survived infancy and were raised in the Mansion. Their youngest child, Alwin, was born in 1901 and lived in the family home until his death in 2004. He died just twelve days before his 103rd birthday.