when do you become genetically male or female
Sexual differentiation in humans Chromosomal sex is determined at the time of fertilization; a chromosome from the sperm cell, either X or Y, fuses with the X chromosome in the egg cell. Gonadal sex refers to the gonads, that is the testis or ovaries, depending on which genes are expressed. Phenotypic sex refers to the structures of the external and internal genitalia.[7]
Anti-Müllerian hormone AMH is activated by SOX9 in the Sertoli cells of the male fetus.[4] Its expression inhibits the development of the female reproductive tract, or Müllerian ducts (paramesonephric ducts), in the male embryo, thereby arresting the development of fallopian tubes, uterus, and upper vagina.[5][6][7][8] AMH expression is critical to sex differentiation at a specific time during fetal development, and appears to be tightly regulated by nuclear receptor SF-1, transcription GATA factors, sex-reversal gene DAX1, and follicle-stimulating hormone (FSH).[9][10][11] Mutations in both the AMH gene and the type II AMH receptor have been shown to cause the persistence of Müllerian derivatives in males that are otherwise normally masculinized.[12]