Sexual characteristics


Sexual characteristics are physical or behavioral traits of an organism which are indicative of its biological sex. These can include sex organs used for reproduction and secondary sex characteristics which distinguish the sexes of a species, but which are not directly part of the reproductive system.

Humans

In humans, sex organs or primary sexual characteristics, which are those a person is born with, can be distinguished from secondary sex characteristics, which develop later in life, usually during puberty. The development of both is controlled by sex hormones produced by the body after the initial fetal stage where the presence or absence of the Y-chromosome and/or the SRY gene determine development.
Hormones that express sexual differentiation in humans include:
The following table lists the widely accepted sexual characteristics in humans:
Humans born with sex characteristics that are in any way from both columns are called intersex.

Invertebrates and plants

In invertebrates and plants, hermaphrodites are common, and in many cases, the norm.
In other varieties of multicellular life sexual characteristics can be much more complex, and may involve many more than two sexes. For details on the sexual characteristics of fungi, see: Hypha and Plasmogamy.