Gender
Genders (or sexes) were a type of variation between different members of a species, with biological and social aspects. Biological sexual differentiation was a central feature of sexual reproduction, the creation of offspring. In many humanoid species, this involved a combination of two or more individuals' genetic material. It was also possible for members of certain species with compatible or related genetic structures to practice interspecies reproduction. Certain cultures facilitated this bonding with some form of a wedding ceremony or other formalized partnership.

Male and female gender  
Humans were considered to be bi-gendered by the Vissians, when it came to sexual reproduction. ()

Many humanoid cultures had a two-sex system based around the division between male and female, or the masculine and the feminine, according to a number of minor anatomical and physiological differences. According to James T. Kirk, the "idea of 'male' and 'female' were universal constants." ()

In explaining the sexes to the androgynous Soren, William T. Riker asserted that in Humans, "physically, men are bigger, stronger in the upper body" and that they "have different sexual organs." He also noted, "Men can't bear young." () Some of these characteristics were present at birth while others emerged at puberty. Other species had different secondary sexual characteristics and physiological features; for example, female Ferengi had smaller ears than males (), while Betazoid and half-Betazoid women experienced a period of increased libido during mid-life, referred to as "the phase". () 

One individual of each sex was typically required for reproduction, in a process called sexual reproduction. (; ) In many animal species, the female initiated the mating ritual. Captain Janeway reminded Tom Paris of this when they hyper-evolved into salamander-like species and produced offspring. ()  

Some more advanced lifeforms also maintained such distinctions. When two members of the Q Continuum chose to practice two-party reproduction, they manifested themselves in such a manner. () Q revealed a scornful attitude toward Human females when he discovered Humans in the Delta Quadrant a century sooner than expected: "This is what happens when you put a woman in the captain's chair!" ()

However, sexuality often went beyond the requirements of reproduction. Many sexually differentiated species exhibited diverse sexual orientations, with a proportion of individuals engaging in sexual and emotional involvement with members of the same gender or multiple genders. (; ).

Interest in different genders might affect the assiduity with which duties were carried out. In 2151, T'Pol queried whether Jonathan Archer would be so determined to locate an apparition were it a "scantily-clad man." ()

Gender had influence on interpersonal relationships other than mating. According to Counselor Deanna Troi, "Human males are unique. Fathers regard their sons as children, even into adulthood. Sons chafe against their fathers' perceived expectations." () William Riker asserted that most people thought that the genders had different emotional outlooks, but that whether they actually did was "the kind of question that might take a lifetime to answer." ()

Gender identity 
Several species had members whose gender identity differed from what was considered typical for their biological makeup. Some species had individuals whose gender identity did not align with the male/female binary, often preferring to be referred to using gender-neutral "they/them" pronouns. The Human Adira Tal was one such individual. (; ) Their partner, Gray Tal, a Trill, was also transgender, his male gender identity differing from that presumed at birth. () 

Conversely, the J'naii species lacked a biological sex distinction; however, some members, such as Soren, self-identified as female or male, and showed attraction based on gender in others (e.g. Humans). For most of the J'naii this was considered a deviant identity, and gendered members of their species were subject to psychotectic treatment that would render them genderless. ()

Coming to openly live an authentic gender identity different to that assigned at birth was known as transitioning. () This could include modification of one's anatomy in accordance with one's sense of gender. By the 24th century, Federation medical technology was capable of surgically providing individuals with the anatomical and hormonal characteristics typical of a different sex than that assigned at birth. This could be done in a single outpatient procedure, and could be similarly promptly reversed. ()

Gender roles 
Many species had norms or patterns regarding the appearance or social roles considered typical of different genders, and some granted different legal or customary rights to members of different genders. 

Upon first being created, the android Lal regarded its non-gendered appearance as making it "inadequate". Data told it this is why it ought to choose a gender, to complete its appearance. ()

Despite their natural anatomy lacking any apparent sexual differentiation, several Changelings presented a consistent gender similar to that of many humanoids when in humanoid form. Odo and Laas presented consistently as male, while the Changeling who chiefly commanded Dominion forces during the Dominion War presented consistently as female. 

William Riker referred to an Earth nursery rhyme, "What Are Little Boys Made Of?", which stated: "Girls are made from sugar and spice, boys are made from snips and snails... and puppy dog tails," to describe an "old-fashioned way of looking at the sexes" to the androgynous Soren. Soren also learned that it was more typical for Human women than men to wear cosmetics, wear their hair long, and wear elaborate hairstyles. () In many species, males and females tended to wear different types of clothing. Worf indicated his displeasure at wearing dress uniforms because he said they looked too much like women's dresses, an attitude which William Riker characterized as "outmoded and sexist." () 

In many sapient species, the gender roles associated with mating went beyond biological differences associated with reproduction. Beverly Crusher told Soren that although women might wear cosmetics to attract men, she believed men were just as interested in attracting women, even if their means of doing so were less conspicuous. () Worf explained that, among Klingons, "Men do not roar. Women roar. Then they hurl heavy objects and claw at you," while the man "reads love poetry" and "ducks a lot." ()

Some societies had beliefs about which genders were better suited to which professions. For example, in Cardassian society, men were more prominent in government and the military, but women were considered more suited than men for the sciences. ()

Roles in the family might depend on gender. Worf once explained, "It is my understanding that in most Human families, the woman shares in the cooking." () 

Some societies considered one gender superior to others, a belief known as sexism. The Ferengi had a strongly patriarchal society in which women were considered property and were not allowed to wear clothing or earn profit. (, ) At least one Ferengi woman, Pel, disguised herself as a man in order to escape these strictures. () These restrictions began to change in the 2370s under Grand Naguses Zek and Rom, notably at the instigation of Ishka, with important legal reforms being passed to improve the status of Ferengi women. () 

Other notably patriarchal societies included the Talarians and the Kazon. (, ) 

Klingon society also had patriarchal elements; women generally could not serve on the Klingon High Council, although there were exceptions. (, ) However, Klingon women wielded unchallenged authority in the functioning of the Great Houses. () Worf agreed with the statement that "women are weak and need more help." (). On another occasion, though, he asserted that Klingon males "appreciate[d] strong women." () 

Conversely, the planet Angel I was considered "an unusual matriarchal society" where the female was aggressively dominant, as well as larger and stronger than the male counterpart. Like other societies in which one gender was dominant, they considered their arrangement most sensible and natural. Deanna Troi said that the matriarchal government of Angel I resembled the society of Betazed. () The Skrreea were a matriarchal society as men were considered too emotional to lead. () Other matriarchal societies included the Paraagans and the inhabitants of Cygnet XIV. (, ) Unusually, while the Orions presented themselves to outworlders as highly patriarchal, they were in fact a matriarchy. ()

Many societies in Earth's past had strongly differentiated roles and rights depending on gender; it was noted that in particular periods, only landowners of a particular gender had any rights at all. () Beverly Crusher noted that although in the past, Human women had been considered weaker and inferior to men, this had not been true for a long time. ()  
Vissian cogenitors had the same learning potential as the male and female sexes. However, it was considered "not right" for one to learn to read. ()

The Trill took a more relaxed attitude than other species to gender role, since joined Trill routinely had had lifetimes as members of both Trill genders. Odan was disappointed to learn that Beverly Crusher was not interested in continuing their romance because her new host, Kareel, was a woman, which Dr. Crusher as a Human found disorienting. () While sparring with Worf, Jadzia Dax told him, "I hope you're not holding back because I'm a woman. If it makes things easier, think of me as a man. I've been one several times!" () That said, Trill society may have been more patriarchal in earlier centuries, as Lela Dax was one of the first women to serve as a councilor in the Trillian government, in the 22nd century. ()

Other variants of sex and gender 
There were also various alien sexual makeups which consisted of different constructs or combinations of sexes:

Androgynous species 

Androgyny, also known as being "genderless" or "neuter", was the absence of distinct genders. A number of androgynous species were known, including the Axanar, the Xindi-Insectoids, the Bynars, and the J'naii, among others. (; )

When considering the health of Sluggo, a slug-like creature discovered by Hoshi Sato in 2151, she referred to it as a "she". However, Doctor Phlox questioned the identifier, stating, "We haven't been able to determine its gender yet, if it has one." ()

Hermaphroditic and transgender species 

Hermaphrodism referred to having the characteristics of two or more sexes. Unlike androgynes, hermaphrodites could function as either a male or a female during sex, or undergo a functional transformation from one gender to another.

During the wedding ceremony of William T. Riker and Deanna Troi, Data also welcomed the "invited transgendered species." ()

More than two sexes or genders 
Some species had more than two sexes, or different capacities were assumed by sexes not conforming to the pattern of male/female bonding which seemed to be common throughout the galaxy.

According to T'Pol, "tri-gender reproduction [was] not uncommon," while Phlox noted that, "Multi-gendered techniques [for reproduction] aren't always the same." For example, Vissians required three separate sexes to reproduce: male, female, and cogenitor. Phlox speculated that "the cogenitor provides an enzyme which facilitates conception," and it was later revealed by a Vissian that cogenitors were "only needed when a couple's trying to have a child," and made up a small percentage of the overall population, about three percent. ()

Species 8472 had as many as five sexes, and Doctor Phlox believed Rigelians to have four or five genders. (; )

Appendices

Background information 
Kate Mulgrew as Captain Janeway was the first female lead actor of a Star Trek series. The first female captain seen on Star Trek was the Saratoga captain seen in , played by Madge Sinclair. While Majel Barrett's character Number One was the first female first officer to appear in Star Trek, it was Nana Visitor's character, Kira Nerys, that was Star Treks first female regular character to serve as first officer. The first pairing of a female captain and a female first officer serving aboard the same starship as each other was the 's Philippa Georgiou and Michael Burnham in  and . ()

According to  and , Andorian marriages typically involved four partners and Bolian marriages might include co-spouses. It was not revealed what, if anything, this said about the genders of the aforementioned species. Only male and female Andorians have been referred to on screen, and no on-screen Andorian child has been referred to as having more than two parents.

In ultimately unused dialogue from the writers' first draft script of , Dr. Phlox tried to reassure Hoshi Sato that his Pyrithian bat bit males only, but Sato wasn't so sure that the bat could tell the difference between genders.

Apocrypha 
Several non-canon novels and comics (such as the DS9 series) have portrayed Andorians as having four distinct sexes required for mating. Other novels portray other cultures having three or more sexes, such as Diane Duane's description of a Horta character as being an "orthomale type B4-A".

External links 
 
 
 

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