Sidis consistently expressed a strong aversion to marriage and traditional societal expectations. He viewed such institutions as restrictive and incompatible with his desire for personal freedom.

Sidis maintained a relatively solitary existence, with limited close friendships or romantic relationships. He valued his independence and preferred to spend his time pursuing his own intellectual interests. Despite claiming to prefer celibacy and solitude, some evidence suggests he desired a close relationship but struggled to form one.

Sidis develops a connection with Martha Foley, a socialist activist. Although details are scarce, some sources suggest she may have been the closest he came to a romantic relationship.

Sidis becomes increasingly estranged from his parents, blaming them for the pressures he faced as a child prodigy and for his commitment to a sanatorium. He felt that their parenting methods, while well-intentioned, ultimately harmed his well-being. He refused to attend his father's funeral.