Irish families as septs of Highland Clans

[O'Callaghan]

I am puzzled by the number fiz-,kirk-, o' and the other common Irish names being listed as septs of Scottish Clans.
I know the obvious , the migration from Ireland brought many of those families over and the clan system integrated them at some point. Also I know that some clans are of Irish origin and that some families and clans share a common name but have different origins -like Kenedy.
Personally , I would like to understand the connection and relationship between the Catholic MacManus-MacMains and the Colquhon clan, other than the fact that the MacMains served the clan there isn't much info.
Gunn and MacManus-MacMains makes more sense because of the Norse-Gael lineage. But that those are questions that relate specifically to me , in general ..I cant find anything but general generic info on the relationship between the clans and the septs that have obvious Irish names.
Does any one have any insight ?

The main migration of Gaels to Scotland from Ireland pre-dates surnames, so even where the name is similar or related there is often no link atall, but of course there were movements in both directions.

Kennedy is a particularly interesting one, as there are not merely two Kennedy clans, but three. As well as the Scots clan, and I suppose all Scottish Gaels were of the Dalriada, there were Irish Kennedys of the Dalcassians and of the Eugenians, these all being tribes of Gaels, for which I have given the anglicised versions of their names. Callahan is a Eugenian name, but the really famous Kennedy clan (think US politics) is Dalcassian, not Eugenian, so not of my tribe. The name Kennedy is simply the anglicised form of the first name Cenneidhe, of course, which I suppose must have been a popular name. Most Gaelic surnames were formed that way. Of course, not all the Scottish clans were Gaelic, whereas I think generally the Irish ones were, but that's another matter.

Not a historian or in any way qualified in what I am talking about, LOL!

[TheMcManus]

The main migration of Gaels to Scotland from Ireland pre-dates surnames, so even where the name is similar or related there is often no link atall, but of course there were movements in both directions.

Kennedy is a particularly interesting one, as there are not merely two Kennedy clans, but three. As well as the Scots clan, and I suppose all Scottish Gaels were of the Dalriada, there were Irish Kennedys of the Dalcassians and of the Eugenians, these all being tribes of Gaels, for which I have given the anglicised versions of their names. Callahan is a Eugenian name, but the really famous Kennedy clan (think US politics) is Dalcassian, not Eugenian, so not of my tribe. The name Kennedy is simply the anglicised form of the first name Cenneidhe, of course, which I suppose must have been a popular name. Most Gaelic surnames were formed that way. Of course, not all the Scottish clans were Gaelic, whereas I think generally the Irish ones were, but that's another matter.

Not a historian or in any way qualified in what I am talking about, LOL!

There were also Scot Kennedys who moved over to Ulster in fiarly sizeable numbers and I am sure Irish Kennedys who moved to Scotland as there large Irish colonies in some areas. I think the Chief of the Kennedy clan , the Highland iteration, had declared that all kennedys from all families have a home in the clan, so that's cool.

[EagleJCS]

I can't give any insight to the OP's question, though I do have a comment.

Scott is also a family name that is of fairly ambiguous origin. I have been told there are at least three different origins (English, Irish, and of course, Scottish), none of which are related to one another. By some published accounts, the Scottish line traces back to one Uchtred filius scoti - Uchtred, son of (the?/a?) Scot - in the early 1100's, witness to the foundation charter of the abbey of Holyrood , among other things.

The Irish and English Scotts presumably derived their family names from ancestors who migrated from Scotland and either referred to themselves as 'Scots' or were referred to by their neighbors as 'the Scot'. (e.g. 'Alex, the Scot' turning into 'Alex Scott' over time). The second 't' was added later as spelling standardization took place, to differentiate the family from the nationality/ethnicity.

Regrettably, my family doesn't know for certain which of the three groups we descend from. A cousin has traced back to pre-Revolutionary western Virginia, but the trail gets a bit confused trying to go back from there. From what I recall, when asked my grandfather always said we were Irish Scotts, then laughed. I think he was making a joke based on the fact that his mother was Irish (from Country Antrim) and the family name is Scott, though there is a distinct possibility that we are, in fact, of Ulster Scots descent. As to where those Scotts may have came from, who knows?

[O'Callaghan]

If it comes to that, I have Hart in my family tree, and the English, Irish and Scottish Harts are all unrelated. The Scottish Harts have their own tartan, but are not considered to be a clan, or even a sept of one, AFAIK. By default, my Hart family is probably of English origin, but all the world tends to move to London, so that is by no means certain.

There are other names in my family tree that might be septs of Scottish clans, if they were only of Scots origin, but they probably aren't. I am sure there are, for example, Americans, who proudly wear a particular tartan because they have people in their family tree who bore a certain name that appears on a sept list, blissfully unaware that their ancestors were unrelated English people with the same name.

OTOH, the Callaghan was one of the small number of Irish clan chiefs that were actually recognised by the Irish government, that is, until they stopped doing that. The Irish constitution specifically prohibits recognising titles of nobility, so it was probably unconstitutional anyway!