Dr. Debra Soh on science: what the evidence says · JRE #1520

What the evidence says 01 / RECORD

Soh claims biological sex is binary because it is defined by gamete type, with no intermediate gametes, and that this applies to 99% of people. It is true that only two gamete types (ova and sperm) exist in humans and no third, intermediate gamete has been documented; a gamete-based definition of sex is a real position argued in the scientific literature, including a 2025 paper in Archives of Sexual Behavior titled "Why There Are Exactly Two Sexes," which has since drawn published rebuttals contesting its framing. However, mainstream biological and medical sources note that sex classification in practice draws on multiple traits, chromosomes, gonads, hormones, and anatomy, that do not always align neatly into two categories; conditions grouped under "differences of sex development" (DSDs) produce anatomical, chromosomal, or hormonal variation in an estimated 0.05% to 1.7% of the population depending on definition. Sex and gender are also distinct concepts in the biomedical and psychological literature, not interchangeable as the claim implies. The specific 99% figure was not sourced or defined by Soh during the discussion and does not correspond to a commonly cited statistic in the literature reviewed. Overall, gamete type is one valid, real biological framework for classifying sex, but presenting it as settling the sex/gender question for "99%" of people, without qualification, oversimplifies documented biological variation and elides the sex/gender distinction.