How many years back would the average person have to go to find common ancestry between them and their spouse?

Merely from personal antedotal experience, I would suggest that if both parents are from the same ethnic group, they only have to go back about 300 to 400 years at most to discover a common ancestor.





Case in point: I can trace both my dad's granddad's maternal line and my mom's maternal line to a Hugh Crawford (1526-1576) of Kilbirnie, Ayrshire, Scotland. I don't have all the information on my dad's mother's ancestors, who arrived in North Carolina from the Isle of Skye off the Scottish coast shortly before the American Revolution, nor do I have all the information on my mother's father's family, many of whom came to the United States from Ayrshire, Scotland, about 1800, but both families came to Texas via the same counties in North Carolina and Alabama and then settled in nearby counties in Northeast Texas, so my parents may be more closely related than eighth cousins, which is what I can trace so far on Ancestry.com. If the famous icon indicator is any indication, they probably share other ancestors as well because I'm related to Robert Louis Stevenson through at least three different lines and to L. M. Montgomery (the author of ';Anne of Green Gables'; through at least two separate lines. I've also dated a gentleman who shared a common ancestor with me who was born about 1710 in Northern Ireland.How many years back would the average person have to go to find common ancestry between them and their spouse?
I've read that 85% of the people wirh English, French or German ancestry (BeNeLux and parts of Switzerland, Austria and Italy as well) are descendants of Charlemagne. He was born about 700 AD, so 1300 years would do it.





This assumes your average person and his spouse are roughly the same race. If a Chinses married a Chilean, you'd have to go back a lot further.How many years back would the average person have to go to find common ancestry between them and their spouse?
I found a couple connections between my line and my husband's going back about 10 generations (1700's - 1800's). On the other hand, my mother's parents shared the same 4th great-grandparents.