A notable sex researcher known for his theory that gender can be nurtured through environment, who is largely responsible for managing Brenda/David's gender reassignment.

Mother of Bruce and Brian, who is deeply involved in pursuing gender reassignment treatment for Bruce after his accident, and later confronts the emotional aftermath of these decisions.

Father of the twins, Bruce and Brian, who supports Janet throughout the medical journey and eventually reveals critical truths to Brenda.

The twin brother of Bruce/Brenda/David, who experiences his own challenges but supports his sibling's transition later in life.

A psychiatrist in Brenda's early adolescence who plays a role in introducing key professionals to help Brenda eventually transition back to David.

A psychiatrist who aids in Brenda's realization of identity and supports the transition to David.

A leading researcher opposing Dr. Money's theories by emphasizing biological factors in gender identity, collaborating with David to challenge previous claims.

A reporter meticulously documenting the complexities of David Reimer's life, striving to provide a balanced viewpoint of the case.

The first psychiatrist assigned to Brenda, initially adherent to Money’s treatment but develops skepticism over time.

A psychiatrist working with Brenda who suggests an eventual truth revealing but exits for maternity leave before seeing it through.

Known for her direct approach, she briefly works with Brenda and immediately criticizes the gender reassignment.

A gynecologist who collaborates with Dr. Money, instrumental in the initial surgical procedures on Bruce.

Brenda’s first school friend who remains loyal and supportive despite their differences.

A junior high friend of Brenda also outcast due to her own physical condition, sharing mutual respect without deep bonding due to differing interests.