Rolfe
Adult human female
IMO anyone can be part of that ethno-cultural group so long as they have lived within that culture and shared the experience of people within that culture. If you grew up in a Scottish community and shared the same experiences as all the Scottish people around you, you should be considered Scottish regardless of your DNA. Conversely someone who hasn't lived that life an hasn't shared those experiences should probably refrain from claiming that culture, even if they share DNA with it, because genetic differences between groups of humans is to small to be relevant.
Not arguing with that. My newsagent is Scottish, despite having 100% Pakistani genetics.
Donald Trump isn't. So there. (Although the comedy sketch on BBC Alba in which the Donald is a Gaelic speaker - he could have been, as his mother was - is in touch with a couson in the Outer Hebrides and phones him - in Gaelic - for advice every week is however hilarious.)