One of the questions which gets asked often is..... is our McCain family, or clan, connected to the Glencoe McCains. No, we are not. We are not related to them at all via the paternal line. Both clans use the same surname, which is how the confusion ensues. We both have the Gaelic surname of Mac Eáin, written MacEain in modern Scots Gaelic. The surname is from the Latin name of Iohannes. The etymology is Latin to Gaelic, hence our name is not from 'John' as that is the English form of Iohannes, and our surname went straight from a Latin loan word into Gaelic.
In the late nineteenth century several histories of our family were published in which it was suggested that we were connected to the Glencoe Mac Eáin family. These early published histories took on a life of their own, so much so, that the error became incorporated in our family lore. Many of us, me included, went out an purchased, very expensive, Clann Dhónaill kilts. At that point we did not know our real history.
As several researchers, myself, my cousin Dr William McCain, and others, such as Jim McKane in Ontario, Joe McKane in Tennessee, began to dig into our early history, we realized that there were several McCain families from Ulster and that the reported link to the Glencoe McCains, had never been verified.
Then came the DNA testing in 2003. By 2004, we did locate the Glencoe McCain family as several of their members participated in the McCain DNA Project. They did not match us, but they did match the Mac Dónaill chiefs, which had already tested in one of the very first DNA projects. So, we found them, but we are not connected to them. Of interest, they are Norse in paternal ancestry, where as our family is Gaelic in paternal ancestry.
I did locate a McCain clan, native to Kilmichael Glassary parish, in Argyll, south of Glencoe. As I was researching them, the McCain DNA project, began to get DNA matches to Kilmichael Glassary parish, lots of them. So using DNA results as a guide I researched 'that' McCain family. As the research stands now, I am satisfied, they are 'our' McCain clan. I use the word clan with intention, as they were a Gaelic 'clann' in the historical sense the word was and is used.
After many delays, I hope to get out the book, Finding the McCains, this spring. I had several delays from summer to winter last year. (those that know the series of great misfortunes that happened to me, know of what I speak). The book will have a very details chapter of the progenitor of our McCain family.
A sidebar..... as many have observed, we have a paternal connection to a large Henry family. In Gaelic that surname is Mac Eanruig and there was a historical Mac Eanruig family native to Kilmichael Glassary family, so it is at least suggestive, that our Henry matches originate with the Kilmichael Glassary Mac Eanruig family. Now they were also the maternal line of the Glencoe McCain family. Which means, it is possible that we do have a very distant maternal connection to the Glencoe McCain family, but it would be very distant indeed, going back to late medieval times.
Summary, we are the Mac Eáin clan of Kilmichael Glassary and have no paternal connections to the Mac Eáin clan of Glencoe.