The effects of genes carried only on the Y chromosome are, of course, expressed only in males.
Most of these genes are the so-called maleness determiners, which are necessary for development of the testes in the fetus.
The X chromosome, being larger, carries many more genes than does the Y.The Berdache in North America, the fa’afafine (Samoan for “the way of a woman”) in the Pacific, and the kathoey in Thailand are all examples of different gender categories that differ from the traditional Western division of people into males and females.Further, among certain North American native communities, gender is seen more in terms of a continuum than categories, with special acknowledgement of “two-spirited” people who encompass both masculine and feminine qualities and characteristics. The tissues sampled for chromosome studies (two skin biopsies, right gonad and blood) contained cells having 46, 47 and 49 chromosomes and XX, XXY and XXYYY sex chromosomes respectively. The chromosomes were studied in a human intersex (“true hermaphrodite”) characterized by ambiguous external genitalia and abdominal gonads consisting of a left ovotestis and a right primitive testis.
The reason for this is that, in each somatic cell of a normal female, one of the X chromosomes is randomly deactivated.