Family alleges OB-GYN used his own sperm for insemination instead of agreed-upon donor’s

Joseph Laedtke, 43, learned through an ancestry test that he had nine half-siblings, who he says connect back to his mother’s fertility doctor from the 1980s.

When Joseph Laedtke got the results of his ancestry DNA test in December 2024, he was shocked to learn he had nine half-siblings. And that they all seemed to trace back to his mother’s former doctor.

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Mary Ellen Lukezich and her late husband, Thomas Laedtke, went to see Dr. Frederick Dettmann in the early 1980s when they were struggling to have a child, she said. The Wisconsin couple spent two years undergoing fertility treatments and eventually agreed to undergo artificial insemination using donor sperm.

She remembered that Dettmann suggested using donor sperm from a medical student. Lukezich told NBC News that she was assured upon asking questions of Dettmann that the donor was unlikely to donate again, that he was from out of state and that he was chosen to closely match her and her husband’s appearance.