His father, Robert, is of Lithuanian origin and played professional football for Woodville-West Torrens in the SANFL.
[1] Jack participated in the Auskick program at Henley[2] and grew up playing high level Australian rules football and cricket in Adelaide for Fulham Cricket Club while attending Henley High School with future Gold Coast teammate Izak Rankine.
[3] Such was his talent in cricket, he was selected as the opening bowler for South Australia at the 2016-17 U17 national carnival but gave the sport away soon after to focus on football.
[4] He made his senior SANFL debut for Woodville-West Torrens in a 2017 preliminary final against Sturt where he finished with 12 disposals, 8 marks and 4 goals.
[5] Leading into his final year of junior football, Lukosius was considered a potential number-one draft pick by many draft analysts[6] and drew comparisons to superstar St Kilda forward Nick Riewoldt.