Sexual characteristics are physical or behavioral traits of an organism (typically of a sexually dimorphic 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.
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Humans
main article: sex differences in 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:
Typical sexual characteristics
The following table lists the widely accepted sexual characteristics in humans:
Humans whose sexual characteristics are ambiguous or mismatched are called intersex.
Invertebrates and plants
In invertebrates and plants, hermaphrodites (which have both male and female sexual characteristics either at the same time or during their life cycle) are common, and in many cases, the norm.
In other varieties of multicellular life (e.g. the fungi division, Basidiomycota) 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.