Aberdeenshire born Stephen started playing rugby a Garioch RFC at the age of six.
He played for his school team Glenalmond College before having his first taste of adult rugby at Aberdeen Grammar Rugby.
In 2023, Seb represented Scotland U18 in the 2023 U18 Six Nations festival before travelling to New Zealand to play for University of Waikato. He returned to Scotland to play for Scotland U20 in the 2024 World Rugby U20 Trophy