It is true that the chromosome is the sex determiner for many species. There are two types of chromosome - X, which determines the female sex, and Y, which determines the male sex. Based on these chromosomes, the child will either be a man or a woman. There are some cases where a person has only one type of a chromosome, X, when they are considered to be an 'inter sex,' although resembling females more. This is different that the usual set of chromosomes - XX for female, and XY for male.