Amara Das Wilhelm (of GALVA108.org) describes the various kinds of homosexual males and females and also the causes of human sexuality and gender in ancient Hindu/Vedic society in his book "Tritiya-Prakriti: People of the Third Sex: Understanding Homosexuality, Transgender Identity, and Intersex Conditions Through Hinduism." :
Homosexual men:
The Five Types of Kliba [Homosexual men]
In a chapter of the Sushruta Samhita (3.2) discussing the conception of
progeny, five types of kliba are listed and described as follows:
1) Asekya—he is aroused only by swallowing a man’s semen.
2) Saugandhika—he is aroused only by smelling the genitals of others.
3) Kumbhika—he takes the passive role in anal sex.
4) Irshyaka—he is aroused only by the jealous feelings of seeing others in the
act of sexual union.
5) Shandha—he has the qualities and behavior of a woman.
The Sushruta Samhita is an ancient Vedic medical text put into writing
sometime around 600 B.C. All five types of kliba are described as inborn,
due to an equal “seed” conception caused by various conditions of the
parents. The Sushruta Samhita distinguishes the shandha from the other four
in that the latter are said to possess semen and male characteristics whereas
the shandha is completely devoid of these. It also mentions that the first four
types of kliba achieve erections through drinking the semen of other men
(3.2.44-45) and describes a type of female shandha with the qualities of a
man (3.2.43).
Homosexual women:
The Ten Types of Nastriya [Homosexual women, which is only the first two, the rest (besides 3) are mainly impotent and not necessarily homosexual]
Women who are impotent with men are mentioned less frequently in Vedic
literature. Nevertheless, at least ten different types of nastriya or third-gender
women can be found in various Sanskrit texts and are listed below.
1) Svairini—she engages in lovemaking with other women.
2) Kamini—she engages in lovemaking with both men and women. ["Kami" is the masculine i.e bisexual male]
3) Stripumsa—she is masculine in behavior and form. [Not necessarily homosexual]
4) Shandhi—she is averse to men and has no menstruation or breasts.
5) Narishandha—her womanhood is completely destroyed.
6) Varta—her female “seed” is afflicted in utero.
7) Sucivaktra or Sucimukhi—she has an extremely small, undeveloped
vagina.
8) Vandhya—her menstruation is absent or suppressed.
9) Moghapuspa—her attempts to unite with the man are fruitless.
10) Putraghni—she has repeated miscarriages.
The svairini is described in the Kama Sutra (2.8); the kamini in the
Bhagavata Purana (5.24.16); the stripumsa in the Mahabharata and various
astrological texts; the shandhi, sucivaktra, vandhya and putraghni in the
Sushruta Samhita (6.38); the shandhi, narishandha, varta, sucimukhi and
putraghni in the Caraka Samhita (4.2; 4.4; 6.30), and the moghapuspa in
various Sanskrit lexicons. The first three types are physically capable of
bearing children whereas the remaining seven are infertile.
The causes of human sexuality and gender:
The Ten Causes of Gender
Both the Sushruta and Caraka Samhitas provide elaborate descriptions
regarding how and why living entities take birth as male, female or third
gender. Such descriptions can be summarized into the ten contributing factors
listed below. In many cases, several or even most of these factors will be
involved to some degree.
1) Samskara—previous life impressions.
2) Kama—desire.
3) Sukarma—good karma.
4) Vikarma—bad karma.
5) Sukra-bala—strength of “seed.”
6) Mithuna-vidhi—method of copulation.
7) Paurusha—the personal efforts of the parents.
8) Dosha—affliction.
9) Prakriti—nature.
10) Daiva—divine ordinance.
1) Samskara—previous life impressions. According to Vedic teachings, the living entity is eternal and experiences innumerable lifetimes until achieving final emancipation. Thus, every newborn person comes with a complete package of previous life impressions, desires and activities known as samskaras. Based on these, the living entity takes birth as male, female or third gender.
2) Kama—desire.
Every living being has kama or innumerable desires as part of the previous life impressions or samskaras mentioned above. When the living entity
desires to experience a lifetime as male, female or third gender, such a lifetime comes to pass.
3) Sukarma—good karma.
When the living entity takes birth as male, female or third gender according
to desire, such a birth is said to be the result of previous good deeds or
sukarma. A birth due to sukarma is evident when the person is happy with
the awarded birth and resides in a setting where he or she is treated kindly.
Such a person is furthermore endowed with auspicious qualities such as
beauty, good health, strength, wealth, talent, intelligence, good parentage,
righteousness, renunciation, religiosity, and so on.
4) Vikarma—bad karma.
When the living entity is forced to take birth as male, female or third gender
against all desire, such a birth is said to be the result of previous misdeeds or
vikarma. A birth due to vikarma is evident when the person is unhappy with
the awarded birth and resides in a setting where he or she is treated harshly.
Such a person is furthermore endowed with inauspicious qualities such as
ugliness, ill health, weakness, poverty, lack of talent, foolishness, bad
parentage, unrighteousness, excessive attachment, irreligiosity, and so on.
5) Sukra-bala—strength of “seed.”
According to the quantity and the quality of the parents’ “seed” at the time of
conception, a child is conceived as male, female or third sex. When the
father’s sukra or male sexual fluids predominate, a male is produced and
when the mother’s sonita or female sexual fluids predominate, the child will
be female. If both are equal, the offspring will be of the third sex. Such equal
“seed” conceptions are further distinguished as follows: When the “seed” is
exactly equal and afflicted, the child will be sterile or have both male and
female physical characteristics; when the “seed” is mostly equal but slightly
more in terms of the male or female, a third-gender boy or girl will be born
respectively, and when the “seed” is mostly equal due to the profuse quantity
and strength of both parents, a bisexual child is born. Thus, according to the
bala or strength of the parents’ sukra and sonita, various types of male,
female and third-gender offspring are produced.
6) Mithuna-vidhi—method of copulation.
According to Vedic science, the mithuna-vidhi or method of copulation can
also determine a child’s gender by affecting the parents’ “seed” and attracting
specific types of living entities to the womb. When upasriptaka or normal
copulation is employed, the child will be either male or female but if
citrarata or exceptional copulation is engaged in, a third-gender child will
likely be the result. Such exceptional methods of copulation are further
distinguished as follows: When the parents assume the purushayita or
“woman on top” position, the offspring will be a male or female shandha
who behaves like the opposite sex; when the wife assumes a complicated
position during intercourse and the husband’s semen is weak, the child born
will be a vakri with a deformed male organ; when the wife performs oral sex
on her husband prior to intercourse and a son is conceived, that boy will be a
mukhebhaga who performs oral sex on men, and if the husband performs oral
sex on his wife prior to intercourse and a daughter is conceived, that girl will
be a svairini who makes love to women. Thus, according to the parents’
mithuna-vidhi or method of copulation, various types of male, female and
third-gender offspring are produced.
7) Paurusha—the personal efforts of the parents.
Parents generally desire heterosexual offspring—especially sons—and Vedic
texts offer many helpful practices to assist them in this regard. The parents
should keep good sexual health, take invigorating tonics, refrain from
overindulgence, assume the upasriptaka or “man on top” position during
intercourse, follow proper timing, observe prescribed rituals, consult
astrologers, propitiate the gods and so on. At the time of conception, the
consciousness of the parents should be peaceful and pure; they must have
passion but not excessive lust, anger or detrimental feelings such as jealousy.
In this way, the parents should apply personal effort or paurusha to conceive
the offspring they desire.
8) Dosha—affliction.
Due to previous misdeeds and despite the best efforts of the parents, various
afflictions or doshas can arise that result in the birth of sterile or malformed
offspring. The word dosha refers to afflictions caused by some imbalance or
aggravation of the three bodily substances known as vata, pitta and kapha
(also called doshas). When afflictions occur in the sex organs, reproductive
fluids, hormones, chromosomes or genes of either the parents or embryo of
any sex, offspring are consequently born sterile or sexually malformed to
various degrees.
9) Prakriti—nature.
When all of the above considerations are taken together they result in the
aggregate factor known as prakriti or nature. The workings of material nature
are subtle and mysterious yet grossly powerful. According to the stringent
laws of prakriti, all living entities are forcibly born among the three genders
in a series of countless lifetimes.
10) Daiva—divine ordinance.
The ultimate factor in regard to cause of gender is daiva or divine ordinance.
Indeed, the laws of nature work according to God’s will and cannot be
overruled. It is therefore daiva or divine ordinance that ultimately determines
which of the three genders a living entity assumes. The various supernatural
causes such as being cursed or blessed by a demigod or saintly person are
also included within this category.
Regardless of one's gender and sexuality, Brahmacharya (celibacy) is necessary for those on the spiritual path.