A long time ago, Doris and I went back and forth on this issue.In the years gone by, I have had the DNA workup done and learned more on the ground in Europe.DNA test by 23 and Me.com
First, my surname is Partain and my most paternal ancestor is tracked to the areas on both Ireland and Scotland across from the Isle of Man in the North Irish Sea.
As another note, the name Pfarthegn, latinized to Partain after conversion to Christianity, is a not-rare Norwegian name.The Pfar is the same as the German "fahren" and related to the English ferry and faire, as in to travel.Thegn is related to the word Thane and means a minor lord.The name Pfarthegn is found spelled in runes in the Stavanger area of Norway, seems to exist at least prior to 600 AD.Modern Norwegians spell it Fartein, as in the name of Fartein Valens the composer.There was much settlement from Norway into Western Scotland, and likely there is some connection -- but i have not had the resources to confirm.See the town of Parton near Castle Douglas in Scotland.
I was also told in Norway that a "partain" was a type of sailor who performed navigation in ancient times.I have no idea about the veracity of that story.
I have also done a more complete job on my genealogy, and as Doris stated, the names Parton/Partin/Parten/Partain drift along and you can find the same folks spelling it differently at different points.Spelling was not apparently a major item in the family.