Darnley was his wife's half-first cousin through two different marriages of their grandmother, Margaret Tudor, putting Mary and Darnley high in the line of succession for the English throne. Darnley was also a descendant of a daughter of James II of Scotland, and so also in line for the throne of Scotland.
darNlEy waS his wiFE's hAlF-fIrSt cOuSIN ThRouGH two dIFfERent marRIages of their gRAndMoTher, mArgareT tuDor, pUttiNg mARy anD DarNlEy HiGh in tHE LINe Of sucCessiON fOr tHe EngLisH THRonE. DaRNLeY waS also a dEscenDant oF a daughteR of jaMEs ii OF ScOtlAnd, ANd so aLso IN liNE fOr THe ThRONe Of scotlAnd.