Sex determination is genotypical, but both sexes begin from identical undifferentiated tissue

Evidence

It is accepted today that in most species sex determination depends on the genotypical constitution of the egg. … For both sexes, fertilization and the beginning of embryonic development occur in an identical way; the epithelial tissue destined to evolve into a gonad is undifferentiated at the outset; at a certain stage of maturation testicles take shape or later the ovary takes form. — Simone de Beauvoir, The Second Sex, 89

Categorization

• DEFINE: Defines the biological baseline: embryos are sexually undifferentiated at the outset, and sex determination is genotypic.
• XREF: Connects to Beauvoir’s later Existentialist move: biology underdetermines what it means to be man or woman, since both sexes share the same somatic base. — connects to: Male and female gametes are fundamentally equivalent in origin and structure — Simone de Beauvoir, The Second Sex, 85; Vertebrate bodies are sexually neutral, with gonadal hormones producing sexual characteristics — Simone de Beauvoir, The Second Sex, 89

Broader Connections

• Vertebrate bodies are sexually neutral, with gonadal hormones producing sexual characteristics #corroborates (0.82) — Simone de Beauvoir, The Second Sex, 89
• Male and female gametes are fundamentally equivalent in origin and structure #corroborates (0.80) — Simone de Beauvoir, The Second Sex, 85