Andorian sexual practices
Andorians are a bi-gendered species which recognizes two primary sexes- male and female. In most respects, they are anatomically and physiologically conformist to the galactic standards of what engenders a male and a female.
Sexual Openness vs. Sexual Conservatism
Andorians do not automatically exclude sensual (or even sexual) contact outside of an intimate relationship. This is more of a social necessity than a biological imperative. During its infancy as a race, Andorians were often isolated by weather and other geological factors. Loved ones could be separated for weeks, months or even years at a time during forced migrations.
These events bred into the Andorian psyche a notion that Humans might be reminded of by a song from the Sexual Revolution of the 20th Century- "Love the One You're With." Many Andorians do not preclude sexual contact among friends. There are a number of Andorian religious and social doctrines that even encourage the 'sharing of heat' as a way to maintain survival, camaraderie and indeed sanity during the long, dark, cold winters that pervade Andor.
To a degree, this openness does chafe against a natural Andorian emotion- envy. Many an Ushaan has been fought between a lover and paramour who feels threatened by the other persons in a relationship. Indeed, a majority of Ushaan even in the modern day revolve around slighted individuals and jealous lovers. Andorians are yet to reconcile their beliefs with their emotions.
Polyamory and Polyamorous Relationships
Polyamory is the standard among Andorians. While it is very common for young Andorians to 'couple,' it is seen as a mark of immaturity that they have not yet found another couple in which to share their lives. Andorians are traditionally expected to marry into groups of four. An important aspect of this is that the marriage is not made up of four singles or a couple and two singles. It is expected that two couples will find each other, fall in love and marry. This collective unit is referred to as a Bondgroup.
While it is important for an Andorian to marry into the Keth, the clarification of that rule is that not all members of the polyamory need be from the same Keth, especially in the modern day. However, there are conservative, tradition-minded elements of Andorian society which strongly prefer single-Keth polyamories.
Dynamics of the Polyamory
Ideally, an Andorian polyamory will be possessed of the four recognized sexual roles or gender roles. As with almost any married couple or group, an Andorian polyamory is intimate with itself, and theoretically should leave no one out. Intimacy is practiced together as often as possible, though Andorians do recognize that this isn't always possible.
Gender Roles vs. Orientation
Andorians do not recognize sexual orientation in quite the same way as Humans. Their concern is not whether a couple is male or female (heterosexual), or same-sex. Andorians bluntly measure a relationship by who is the active and who is the passive partner. The gender of those involved is unimportant.
Andorians are as capable of varied sexual preferences as any species. They have reconciled this by acknowledging it but also by trying to reiterate the need for healthy, viable Andorians to reproduce to continue the species. Even same-sex couples and polyamories are expected to do so in some form.
It is vital to understand that Andorians recognize four distinct sexual/gender roles, and two genders. They are as follows, along with their attached prefixes.
Chan - ch' - The 'active' male role.
Thaan - th' - The 'passive' male role.
Shen - sh' - The 'active' female role.
Zhen - zh' - the 'passive' female role.
Gender Role Distinction
Some Keths openly display the gender role of an Andorian by adding a prefix to the name (as above). Other Keths do not require such a thing, or may add the title exclusively when among all-Andorian groups. As Keth are free to govern such things individually, there has never been a consensus as a whole on the issue.
Andorians accept the terms 'male' and 'female' and 'he' or 'she' when dealing with non-Andorian races. Among themselves, it is more complicated.
Views of Nudity and Public Affection
Andorians do not hold nudity and affection in quite the same light as Humans, at least not when in all-Andorian groups.
On Andor and among most Andorian colonies, nudity enjoys a relaxed standard. Communal sunbathing, engaging in sports and a number of rituals and events are expected to be practiced in the nude. These include formal religious ceremonies and marriages. Ushaan, the Andorian form of dueling, is traditionally practiced while disrobed as well.
Amdanalnar, a form of Andorian mimed mystery play, is purposefully done while nude, with the participants wearing only body paint to differentiate their roles within the play.
Generations of communal living have made Andorians more tolerant of public displays of affection. In the past there was simply no privacy. However, blatant sexual contact in public is generally frowned upon, save for a handful of seasonal festivals. Specifically these are a series of fertility festivals to recognize the coming of Spring.
Andorians go beyond merely frowning on interspecies relationships. The camaraderie and liberality of Andorian sexual practices is rendered virtually dead when it comes to sharing those same practices with non-Andorians.
As a species, Andorians remain rather xenophobic. They do not trust non-Andorian races, and even in the present day there are undertones of distrust towards their own sub-ethnicity, the Aenar. Andorians are a rarity among Starfleet and even among mixed Federation worlds because of this social distrust.
Andorians have a strong loyalty to their Keth, and their race. Non-Andorians introduce an unstable and often unwanted element to the mix. Non-Andorians cannot be members of a Keth, and thus being intimate with one is considered a betrayal of the Keth.
Andorians are also one of the least populace species within the Federation- their homeworld is too cold and harsh to allow for large numbers. This has made modern Andorians very touchy about the idea of intermingling with aliens.
Andorians who do engage in interspecies relationships walk an extremely thin line. They must assure that their "indiscretions" are not capable of being traced back to the leaders of their Keth.
Andorians who are suspected of interspecies relationships are often watched and warned by their fellow Andorians, particularly those of their own Keth. They are reminded that such behavior is considered 'dishonorable' and a shameful act not only for the Andorian, but for the Keth itself. No Andorian wants to shame his or her Keth, after all.
If an Andorian is "caught in the act" they can face disciplinary action. Usually this takes the form of censorship and temporary exile from Keth-held territories. A repentant Andorian would more likely be publicly chastised and allowed his dishonor be laid bare.
An unrepentant or multiple offending Andorian is likely to face expulsion from their Keth, and possible exile from Andor itself. This is a foregone conclusion if their actions have caused Issue with their non-Andorian partner.
The above is an attempt to reconcile the varied and often disparate fictional works regarding Andorian sexuality and biology. It is not the defining word on the Andorians as a whole, but instead merely the preferred approach to the Andorians by the sole current Andorian character player of the Starbase 47: Tesla roleplaying game. Should any new player wish to review and discuss this approach, feel free to contact Thallin Sesh's player directly.
Specifically removed from this approach is the notion that four genders are required for Andorians to procreate. This is not biologically sustainable beyond a few generations, and thus has been discounted as probable by this writer.
It is canonically known that Andorians marry into groups of four. In the TNG episode Data's Day (4.11), Lieutenant Commander Data notes this fact.