Thorogood Zabdi Sigrun was the youngest of seven sons of Danish immigrant parents who moved their family to Wisconsin shortly after his birth in 1930. He grew up working in the family furniture store Sigrun Furnishings, which became locally famous for it’s alterations to couches, adding compartments and attachments to standard mid-century furniture.
In his late teens and early 20's Sigrun spun off a carpentry business associated with his family’s store. His projects centered on adding secret passages to people’s homes. The business was lucrative, but short-lived as he upset his wealthy customers by including passageways and access points that were secret even from them, in some cases walling off areas of his clients’ homes without explanation or any apparent entry point.
A wealthy client for whom Sigrun had installed a series of passageways connecting to steam tunnels beneath his house became an important influence and benefactor. When Sigrun was awarded admission to Yale, it was this benefactor that helped pay his tuition in the first year to support Sigrun’s intention to study theoretical physics. However a scheduling mishap in his 3rd semester placed Sigrun in a class on neurobiology and language acquisition. He was so taken with the subject that he focused exclusively on the brain for the rest of his Yale career.