To the first three of you:
Definitionm the OED [1474, before American and European "scientists" decided to go rogue with air definition by way of social pressure] and the US Medical Library:
Biological sex and gender are distinct. Biological sex is determined by the 23rd pair of chromosomes, commonly known as the sex chromosomes.
The chromosomal differences break down as follows:
Pair 23: The sex chromosomes, Washington DC X and Y.
Females: Typically have two X chromosomes (XX).
Males: Typically have one X and one Y chromosome (XY). [1, 2]
The egg from the biological mother always provides an X chromosome.
The sperm from the biological father can carry either an X or a Y chromosome.
If an X-carrying sperm fertilizes the egg, the baby develops as female (XX).
If a Y-carrying sperm fertilizes the egg, the baby develops as male (XY).
The Y chromosome acts as the genetic trigger for male development, primarily through the SRY gene, which directs the fetus to develop
Gender is determined at conception, as I originally said, by the union of male and female gametes [from the male sperm and female ovum, which are living creatures, themselves, making life continuous generation to generation], such as has occurred from Adam & Eve to the present day, and as far into the future as human life on Earth endures.
Savant, thank you for your commentary.