Everyone knows how wild and clannish the Scots of the 1st century were--and still are some say. The reason the two Roman walls were built across the Island was because the Romans decided it was safer/easier to wall them out than to try and conquer them.
That being said, how likely was it that occupying Roman soldiers would have been allowed to take land and live in peace once the Roman armies dissolved/withdrew? There was never any peace among the clans, so why would they tolerate outside interlopers?
And I don't see any outsider and former foe being inducted into a clan, even if he'd gotten a maiden with child. More likely, he'd have been killed.
well you have to remember there was military presence for centuries, and soldiers dropping their DNA in the brothel and wife pot, retiring, etc, all during this time, so even if when legions retreated suriving retirees went south (who knows, possibly not), the DNA impact over generations of mixing would remain.
Well, forts full of handsome young soldiers with money to spend do seem to have a way of acquiring "camp followers," that is to say, women of easy virtue. ;^)
'Tis the way of the world . . . .
They still are. I know, my wife is Scots.