The story
Scottish habitational surname for someone coming from The Mearns, an alternative name for Kincardineshire, which is named as An Mhaoirne in Scottish Gaelic, from maor (“bailiff, steward, beadle”). According to Taylor (2006), perhaps ultimately from Pictish (cf. Welsh maeroni (“the office or district of a steward”).
Etymology from Wiktionary, CC BY-SA 4.0.