Sexuality Is Fluid Gender Is Immutable
Women have 28 trillion cells all with XX chromosomes; and males have 36 trillion cells with XY chromosomes. The Y chromosome carries genes that are involved in basic cellular functions. In females, most genes on one of the two X chromosomes are silenced in every cell. This inactivation makes each female a functional mosaic because some cells express one X chromosome, and other cells express the other. The advantages of heterozygosity can be amplified by selection against cells in which the active X chromosome carries a detrimental allele.
