Lots of idle speculation here. I have spent thousands of hours working on my own genealogy for 20 some years. I always went to the source records-births, deaths, marriages, census, land registry, wills, local history books, military files, land grants, etc. Family lore is often wrong. Some, particularly the French Canadians were very meticulous about keeping records. I can trace ancestors back there to the 1600s. DNA testing is just another tool but it can certainly shed some useful information if you use Ancestry.com to do it as they have by far the largest data base. I have visited most of the places my ancestors came from-6 Canadian provinces, Minnesota, England , Scotland, Ireland, the West Indies. In England I found graves of definite ancestors who died in the early 1700s and ancient wills where family connections are described in detail. Some of the English wills were so old I had to get them translated as the language has changed so much over hundreds of years. Along the way I have come across distant cousins through out Canada, parts of the US, England, Scotland, New Zealand, Australia. Some of them had invaluable information. I have only been to Salt Lake City (where they literally have mountains of information) once but I have accessed their information many times.
Dit names can be confusing but with a lot of research they can be sorted out.
On Genealogy boards you come across distant relatives who have a lot of information as some of them have been doing their genealogy for 40, 50 years. But you have to be careful sorting out speculation from the facts.