Everyone knows the whole 'Mac/Mc' is a Gaelic way of saying 'Son of' and everything, but I'm pretty sure 'Mac' was mainly a Scottish thing and as Scottish surnames became present in Ireland, they just changed slightly (as all names do). So the "Mc's" are sort of a more 'recent' Irishization of Scottish names. Me thinks, anyway. Basically anyone with a Mc/Mac surname has every right to claim Irish and Scottish heritage. Or just plain 'British' to put it in a wider spectrum.