Testing firm DNA Clinics "analysed the results of 5,000 tests selected randomly from those it conducted for clients between January 2014 and June 2016.
The results show 48% or 2,396 of UK men tested were not the biological father."
A common reason why a man is motivated to take a paternity test is that a woman has identified him as the biological father and is seeking to live off of him based on that claim.
So a paternity test result is often highly consequential.
Imagine how much cuckolding happened throughout the 99.9% of humanity's existence in which paternity testing was unavailable.