Sjaak (Drs. J.S.H.) Duin worked at Ahold Delhaize in Zaandam—the company behind well-known Dutch retail chains such as Albert Heijn, Etos, and Gall & Gall—until his retirement in 2021. After completing secondary school in Hoorn, he studied econometrics at Vrije Universiteit Amsterdam. He began his career in a research role focused on international bank lending. In the late 1980s, he joined Ahold Delhaize, where he held various positions in finance and IT. Around the turn of the century, he was responsible for managing Ahold Delhaize’s transition to the euro currency. In 2002, he moved to the company's affiliated pension fund, overseeing pension administration, IT, and communications.

Throughout his career, Sjaak engaged in various volunteer activities, ranging from cooperative solar park initiatives to establishing a fibre-optic network in Bergen. More recently, he served on the board of the Kunst10Daagse, a figurative art event in Bergen with a history as long as that of IHMS.

Sjaak has lived in Bergen since 1988 and, since 2014, on the edge of the village.