#7. Genes and chromosomes
Males and females are different from the very moment of conception. Each has 23 pairs of
chromosomes, which carry the body’s 20,000 to 25,000 genes. Twenty-two of these pairs are present in
both males and females, but the 23rd separates the sexes. This final pair contains the sex chromosomes.
In women, both members of the pair are X chromosomes, but in men one is an X and the other a Y.
In addition, if a woman has a disease-producing gene on one of her X chromosomes, it may be
counterbalanced by a normal gene on the other X, but if a man has the same bad gene on his X
chromosome, he lacks the potential protection of a matching gene.