Human Gender Behavior is far more Diverse than the Binary Categories of Male and Female

This article challenges the idea that sex and gender are interchangeable, especially in humans. While classical biology often treats them similarly in animals, human gender behavior is far more diverse than the binary categories of male and female. The paper proposes a three-pillar framework for understanding gender: (1) sex-determining genes, (2) cognitive memory systems involving cellular electrical activity, and (3) a largely overlooked factor—sex-specific calcium (Ca²⁺) homeostasis, referred to as the Calcigender concept. It argues that individual differences in Ca²⁺ regulation contribute to personalized gender behaviors, making traditional labels like heterosexual, homosexual, or transgender overly simplistic and potentially misleading.