Lynsey Sharp was born in Dumfries, Scotland and lived her early life in nearby Lochmaben. She is the daughter of former Scottish athletes Cameron Sharp and Carol Sharp (née Lightfoot). Her father won a 1982 European silver medal in the 200 m and competed at the 1980 Olympic Games, while her mother has an 800 m best of 2:02.91 and competed at the 1982 Commonwealth Games.