You unless you have a twin there is only one of you. Two parents, four grandparents, 8GG, 16GGG, 32GGGG, 64GGGGG, etc. At some point the number exceeds the number of humans on Earth. We know from genetic studies that we (all humans) have common ancestors, mathmatically that may be no farther back than the time of Christ. We (us humans) are all blood kin.

King Henry the Third (IIRC) had eight children. Guess what? 80% of all Englishmen can trace their roots to him. Yes, that is right, 80%+ of England is noble.

Lets go back to pictland around 700AD, the last Picts were Christianized and something like recorded history starts. We know that these people had already been there from the Neolithic times. These people were matralinial and decent was from mother to child. Mixed in there were the Irish who were patrilinial. We decend from and inheirit from both sides. We are direct decendants of Irish Kings and Pictish Queens. Keep in mind that we have royal blood in and out of our lines for thousands of years.

So here you are doing your Geneology and you get to ancestor "Argyle Mac Donal" of the Mc Donnell of Sleet Clan, who you think is your GGGGGGGranddad but you made a mistake and this guy is not your sire but his third cousin Angus McDonnell is instead. Well go back a little way the their common GGranddad and you get back to the same line anyway. Arguements that any mistake no matter how small utterly distroy your geneology is well... BS! Working forward that is true but working backward is is not.

Let me give you an example from my geneology there were 5 families of "Donnell" in Guilliford NC now we know that 4 of them were close kin, brothers, nephews that sort of thing. The fifth bunch of "Donnell" we can not tie conclusively to the other 4. Well Robert Donnell married Anne Donnell. Either he married his sister or more likely one of the Donnell girls from the other 4 families. Now my cousin says to not let the 5th family confuse you there is no tie in. Well look we are not talking about the name "Smith" here, there is a 100% chance that these 5 families are related and if they weren't before they are related by marrage now so what is the differance? Nothing.

My Father is of Scots decent, my Mother is of Scots decent. Yeah there is a little sprinkling of Dutch, German and English names mixed in but the bulk point to Scotland. I am a Scot on my Dad's side and a Pict on Mom's. So are we all.