BashLad, I don't believe you're right when you say that the results show where people related to me now live. If that were so it would mean that my ethnicity is 80% North American with a bit of Australian and New Zealand thrown in.
What I am prepared to believe is that it's a statistical analysis of where people (mainly in North America because that's where Ancestry is based and where most of its customers are) say their ancestors came from. But do they know? Just because a family sailed from Liverpool three generations ago does not mean it was originally from Lancashire.
If I could get all my lines back 7 generations I might start to get a picture of their origins. But there was a lot of migration before that, e.g. Huguenots (not all from France). I would need to look 10 generations ago, but how many of us can trace our ancestors back that far -- even assuming all were faithful to their spouses?
Talking of which, I have several matches that neither I nor the other person can explain, so I'm sure there was some hanky-panky going on somewhere (possibly in several places).
At the risk of being patronising this is probably where indigenous european genealogy probably differs from our colonial cousins. There are very few branches of my tree where I
don't know where my ancestors lived 7 generations ago. The gaps that do exist are down to illegitemacies I haven't yet cracked, but I suspect they didn't travel from the other side of the planet, or they're Irish. Incidentally my ancestor who was born in Liverpool 5 generations ago
did have ancestors there in generations 6,7,8 and 9 but in fairness he was also partly Irish.
When these gene tests test an american and it says 20% of his ancestry is scandanavian they're not saying that based on some sort of self-reporting - they're literally comparing that genome against the population of
present day Scandanavia and finding a certain degree of similarity. It's predicated on the assumption that while there may be many Americans, Australians, other New Worlders of Scandanavian descent there aren't going to be many Scandanaivans themselves of New World descent.
When peoples ethnic breakdowns shift that's largely because more people in the Old World have done these tests and they've got a bigger datapool to sample against.
Like I posted in my own ethnic breakdown when I look at my GGGGG-grandparents generation 8/128 lived and died in Cornwall (6.25%). 8/128 lived and died in Suffolk (East Anglia)(6.25%). 4/128 born and died in Cumberland and Westmorland (Cumbria) (3.125%). 65/128 were born in Lancashire (50.8%) (NW England). The test isn't perfect but considering the size of the area they're targeting and the historical depth frankly I'm bloody impressed with them. My last ancestor born in Cornwall was born there in 1870 but it looks like he left his mark in my genes - the testing company doesn't know anything about my tree.