For clarification, the theory was Chevelier John Alexander McCaughan's. I won't conclude anything without proof and the only real way is to DNA test several males with a derivitive of the MacEachan name. There is one other notable MacEachan clan not related to the Manx Kaighins. They are the MacEachans of Clanranald of MacDonald and are descended from Eachann MacRory, born c.1450, the second son of Roderick (Rory) MacAllen, third chief of ClanRanald of MacDonald. They held lands in Moidart and Ardnamurchan. Since Kaighins showed up in Man prior to 1100, the myth that Kaighins are MacDonalds is rubbish. If you go online to any of those Coat of Arms or "fast fact" genealogy sites, Kaighins are listed under MacDonald. Its unfortunate that I've heard other Kaighins say they thought this was true and some have died thinking this.