A DNA study of 100 men named Robson in Northern England proved that only half could claim descent from a common ancestor.
The study revealed 50 volunteers who gave DNA samples could be tracked back to a single male 2000 years ago.
But others could be descended from hangers-on who latched themselves to the powerful Border Reiver family and changed their names as a form of subservience. [Link]
One of my colleagues is a Robson. I sent him the article.
Wow,
Someone needs to create a web site devoted just for the "Hangers-On" who have adopted the surname of others.
J
My own family name has some "hangers-on." A dubious character named Jonathan Singletary took the name "Dunham" while living in Plymouth Colony in the mid-17th century. In 1683, he was publicly whipped and then kicked out of the colony for killing a guy's dog and nearly setting his house on fire.
He later moved to New Jersey and founded a large family using his pilfered surname.