Biological sex in humans is determined by the two gametes for sexual reproduction — sperm (male) and ovum/egg (female).
While there are intersex conditions in which reproductive anatomy may be ambiguous or not fully formed, none of these conditions constitutes an additional biological sex because they do not produce an additional gamete that is functional for sexual reproduction.
In this video Dan Kuebler offers a biologist’s perspective on what has become a controversial subject. Regardless of one’s position on the relationship between sex and gender, an understanding of what biologically constitutes male or female in humans is essential.
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