McGlynn is the younger brother of [[Conor McGlynn]], who is also a professional soccer player for [[USL Championship]] club [[HartfordRhode AthleticIsland FC]].<ref name="union1"/> On July 25, 2020, both Jack and Conor played against each other for [[Philadelphia Union II]] and Hartford Athletic respectively in the USL Championship.<ref>{{cite web |title=Hartford Athletic 3–2 Philadelphia Union II |url=https://int.soccerway.com/matches/2020/07/26/united-states/mls-reserve-league/hartford-athletic/bethlehem-steel/3284071/ |website=Soccerway}}</ref> They played against each other again on September 23, in which Jack scored the equalizer for Union II in a 1–1 draw.<ref>{{cite web |title=Harford Athletic 1–1 Philadelphia Union II |url=https://int.soccerway.com/matches/2020/09/24/united-states/mls-reserve-league/hartford-athletic/bethlehem-steel/3284122/ |website=Soccerway}}</ref>