The child, a boy, was born severely handicapped and for years the father lovingly cared for him. Then during a routine blood test, the mistake was finally discovered.
As a precaution in the event the boy might someday need a blood transfusion, blood samples were taken from both parents to determine their respective blood types. That is when doctors realized the man could not possibly be the boy's biological father.
Since the couple are now divorced, the discovery was of great significance in determining if he should be responsible for child support payments. A Munich court decided the ex-husband need not pay for the continued care of the boy.
A court spokeswoman pointed out that the man only wanted a "declaration of his legal position." He has never outrightedly stated he will stop supporting the boy.
Under German law it is unlikely the mother could file a malpractice suit against the doctor. So many years have lapsed since the discovery of the mix up, it is also impossible to find the boy's biological father. Even if he were found, he could not be made to pay support for the child.
I think the man loves this boy as his own, no matter what, and will actually continue to make child support payments.