Do you think two persons of the same ethnicity and share the same surname are actually related?

Question

Do you think two persons of the same ethnicity and share the same surname are actually related?
For example Two German American men, initially strangers to each other, find that they share the same surname. Do you think they are actually related, i.e., distant relatives? If not, how could they have the same surname? Lets say there are no adoptions in their families history. I asked this question since I found that President Franklin Delano Roosevelt and his wife Anna Eleanor Roosevelt Note that they Roosevelt surname by birth were actually distant cousins. So, I wonder whether people of same ethnicity and surname are actually related by birth.

Answer

It just depends. The rarer the surname, the greater the chance that they are related by a common ancestor with that name. If two people come from the same region and have a common last name, then that also means they are more likely to be related. brbrThe Roosevelts would be a good example of a nobrainer family connection, had they met as total strangers to each other, and could only confirm they were both from the New England area, but they were in fact both born in New York City and had met as children. brbrHowever, this isnt always the case. For instance, Welsh surnames cannot be trusted. Llywellyn from Wales, whose father was named Evan would have the name Llywellyn Evans. Their next door neighbour, who is also named Evan, has a son called Thomas. Thomas would be known as Thomas Evans. So, in fact, youd have a Llywellyn Evans and a Thomas Evans living in the same town, on the same street, with no connection to each other. brbrThis was how people were known in Wales until one fine day the King of England declared that everyone must have a defined surname so the taking of your fathers name stopped. Therefore, Llywellyn Evans grew up and had a son, David Evans. Davids son was William Evans, and so on. Im descended from at least two different Williams families. DNA testing has shown they have no connection to each other whatsoever, even though both families moved from Wales to Virginia to Southern Indiana.brbrPeople with occupational names like Taylor, Butcher, Baker, and Cook are also not necessarily related. The same could be said of the color names, like Black, Brown, White and Green. Those surnames sprang independently from familial connections.