Jean's father married three times. The first wife died without issue leaving a question of whether Jean's mother was Elizabeth Wemyss or Sarah Douglas. That it could be Elizabeth is doubtful as she did not marry George until 1594 at the earliest and if a year of mourning had been observed, not until 1595. George married Sarah by 1596 so there was little time for more than one child and it is quite likely that she died in childbirth possibly along with her child. It is known that George's second eldest son was born in 1600 leaving it an open question as to the mother of the eldest son William. His birth had to have been from 1595-1599 and there is also the question of Elizabeth. Certainly, at least two of these three were children of Sarah.
Jean's daughter Mary was born before 1614 and one can infer that Jean was born prior to 1601.
Sources
↑
Warden, Alexander J,"Angus or Forfarshire the Land and People, Descriptive and Historical", Dundee: Charles Alexander & Co, 1880, Vol. I, Archive.org,
p. 298
↑ 2.02.1
Hill, William Henry, "Early Records of an Old Glasgow Family", Glasgow: University Press, 1902, Archive.org,
p. 108