[The proof of paternity. An andrological-forensic challenge in historical perspective].

For centuries, difficulties have occurred in determining unresolved paternities. In addition to the modern standard methods, such as the examination of DNA or serological proof, expert opinion on fertility once played an important role. The andrological difference between incapability to fertilise and the inability to participate in sexual intercourse was also distinguished historically. Of special significance was the discovery of spermatozoa by the medical student Johan Ham in 1677 and their further investigation by Antoni van Leeuwenhoek.Recently, modern DNA methods have also been applied for historical investigations. Illustrious examples are the DNA analysis in the case of Kaspar Hauser of Ansbach and the dispute about Thomas Jefferson, President of the U.S., fathering a child by one of his slaves. In this discourse, a medicinal-forensic review of the development of expert opinion, illustrated with historical case studies, is given.