Sex in biology is defined essentially by role in sexual reproduction at the cellular level, gametes specifically. Reproduction is _the_ most important concept in biology and natural history because species reproduction is central to species perpetuation . The other bodily organs , including brain are auxiliary to the gonadal sexes in defining sex in biology.

Sex in biology is defined essentially by role in sexual reproduction at the cellular level, gametes specifically, Leila . Reproduction is _the_ most important concept in biology and natural history because species reproduction is central to species perpetuation . The other bodily organs , including brain are auxiliary to the gonadal sexes in defining sex in biology.

Sex is not the same thing as gender . Third _genders _ are ancient. Homosexuals constitute a third gender There have always been third genders , not sexes , if only to accommodate inter"sexism". You may say I contradict myself. No, there are still only two roles in biological sex at the gamete level. There is no intersex at the gamete level. Also, an individual not born as intersex, cannot transfer from one to the other biological sex at the gamete and defining level .

Finally , intersex births are extremely rare such that it is not wrong to refer to non-inter-sex births as "normal"; it is of course a statistical term anyway, "normal".

"Sex is the trait that determines whether a sexually reproducing organism produces male or female gametes.[1][2][3] During sexual reproduction, a male and a female gamete fuse to form a zygote, which develops into an offspring that inherits traits from each parent. By convention, organisms that produce smaller, more mobile gametes (spermatozoa, sperm) are called male, while organisms that produce produce larger, non-mobile gametes (ova, often called egg cells) are called female.[4] An organism that produces both types of gamete is hermaphrodite.[3][5]"