New here - need help with understanding Clans

[O'Callaghan]

My wife and I are English, although we live in the US. My wife's claim to belong to Clan Davidson is that she was told as much by her Scottish maternal grandmother, maiden name Davidson. That's good enough for me.

Callaghan is my mother's fathers family name, and also the title of one of only a dozen Irish clan chiefs recognised by the Irish government, when they used to recognise such chiefs. This was almost certainly always unconstitutional, as the Irish constitution forbids recognition of titles of nobility, which is rather ironic, as it does not exclude Irish titles.

[ThistleDown]

My wife and I are English, although we live in the US. My wife's claim to belong to Clan Davidson is that she was told as much by her Scottish maternal grandmother, maiden name Davidson. That's good enough for me.

Go for it. We should all believe everything our grannies told us. Mind you, at the time your wife's granny was alive there was no chief of Davidson, so in fact the 'clan' Davidson was broken and didn't then exist. It does now, under Davidson of Davidston, descended from a Davidson of Tulloch. He lives in New Zealand. There is also a pretty lively Davidson Society based in the UK with its own Museum at Tulloch Castle Hotel.

All this really to help the OP understand clans.