When Angela Collins and her partner wanted to have a child, they reached out to a sperm bank in Georgia to look for potential donors. They thought they had found the perfect match in Donor 9623, described as a man with an I.Q. of 160 who was healthy and working toward his Ph.D.

But in 2014, about seven years after Ms. Collins gave birth to their son, she and her partner, Elizabeth Hanson, made an upsetting discovery after learning the man’s identity through a donor sibling group. The donor had a history of mental illness and a criminal record, and had exaggerated his educational accomplishments, they say.

“It was like a lead ball went to the bottom of our stomach for both my partner and I,” Ms. Collins said in a radio interview last week with “As It Happens” on the Canadian network CBC.

She added, “We know nobody is perfect, but we didn’t sign up to choose knowingly that our donor had schizophrenia.”