Milwaukee, Wisconsin — A man who turned to a DNA testing website decades after his birth says he uncovered a deeply personal secret about his biological identity: the fertility doctor his mother trusted in the early 1980s was allegedly his biological father.
The revelation has now led to a lawsuit accusing Dr. Frederick Dettmann of deceiving a patient about the identity of her sperm donor and allegedly using his own sperm without her knowledge.
DNA Test Leads Man to His Fertility Doctor
Joseph Laedtke Heider, now in his 40s, made the discovery in 2024 after submitting his DNA to Ancestry.com, according to the lawsuit filed in Milwaukee Circuit Court.
The genetic results allegedly pointed directly to Dettmann as Heider’s biological father.
For Heider, the discovery was particularly shocking because his mother had been told something very different about the man whose sperm was used to conceive him.
Heider said the DNA evidence forced him to reconsider a fundamental part of his identity.
“Words cannot fully express what it feels like to learn that your entire identity is built on a lie.”
Mother Was Allegedly Promised an Anonymous Medical Student
According to the lawsuit, Mary Ellen Lukezich was a patient at Dettmann’s fertility clinic during the early 1980s.
The lawsuit alleges that Dettmann told Lukezich that the sperm donor was a healthy young medical student who wanted to remain anonymous.
Lukezich apparently believed that information when she became pregnant and later gave birth to Heider. But decades later, the family’s understanding of Heider’s biological origins allegedly changed dramatically after the DNA testing.
Heider said the person identified through the genetic evidence was not an anonymous medical student at all, but the doctor his mother had trusted to help her become a parent.
Lawsuit Accuses Doctor of Exploiting Patient’s Trust
Attorney Al Foeckler filed the lawsuit on behalf of Heider and Lukezich.
The case names Dettmann as a defendant, along with the Wisconsin Health Care Liability Insurance Plan and ABC Insurance Co., according to court records.
Foeckler argued that fertility patients place extraordinary trust in physicians because they depend on them during an intensely personal and emotional process.
He accused Dettmann of allegedly taking advantage of that trust and the vulnerability of patients seeking help to have children. The lawsuit seeks to hold the retired physician accountable for the alleged deception and its impact on both mother and son.
Son Says Discovery Changed His Understanding of His Life
For Heider, the alleged deception is about more than simply learning the identity of his biological father.
He said discovering the truth forced him to confront the possibility that the circumstances surrounding his conception were fundamentally different from what his family had been told.
His comments suggest that the revelation has affected how he understands his own history and identity.
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The lawsuit represents an attempt by Heider and his mother to obtain accountability for what they allege happened nearly half a century ago.
Doctor Denies Allegations
Dettmann has since retired and is now 91 years old. Through attorneys, he has denied wrongdoing.
A statement released by his lawyers emphasized the amount of time that has passed since the alleged events and said Dettmann has no independent recollection of the individuals involved.
His attorneys also said he is unaware of evidence supporting the allegations made in the lawsuit.
The case therefore remains disputed, with the plaintiffs alleging that DNA evidence uncovered the truth while the retired doctor denies wrongdoing.
The lawsuit will now proceed through the legal system, where the allegations and evidence can be examined.
What do you think about this case?
Should fertility clinics face stronger protections and recordkeeping requirements to ensure patients know the truth about donor identities and biological parentage? Share your thoughts in the comments below.
