A question was raised by a customer about marriage and sexuality in the StarCluster, prompted by President Obama's recent words on the subject. My response was as follows:
I am just the game designer, not your group, but here are my thoughts on the matter, speaking as the GM for more than one group. Generally speaking, the Cluster is an extremely high tech place. On many worlds, gender is an entirely elective, and temporary, thing. Within a relatively short time period, a biologically male body can be transformed into a biologically female body, and vice versa. A soul from one body can be transferred to another body, either switching with another soul, or multiply cohabiting that body, and either permanently or temporarily. Body shape is arbitrary - it can be changed before or after birth into whatever is wished - if you can afford it. In that kind of environment, legislating restrictive barriers to interpersonal relations is futile and unrealistic.
Generally speaking, what we currently call marriage is considered two separate issues in the Cluster. One is contract law, and the other is religious. In the Cluster, you can make any contract you wish, with anyone you want, so long as the participants meet the local - as in legal jurisdiction - definition of "adult", and are entering into the contract of their own free will. You can contract a relationship with 2 female humans, one male human, a heavily modified genderless human, two Olphalects from Jom, an uplifted cat, and a robot. That's your choice, and reflects only your taste. These contracts spell out the restrictions, benefits, and responsibilities of that relationship. There are standard legal *types* of relationships, which can save time and money in setting them up, but a legal relationship is entirely arbitrary.
Some people also have religious relationships. These, of course, vary enormously with the religion, but tend not to vary much within the religion. All religions have at least one type of legal relationship which is encouraged, and may have some which are forbidden. That's up to the religion, and religious relationships have no legal significance. If the religion's standards are not for you, you can agitate for change from within, or leave the religion as you choose. If you violate those standards while within the religion, that is a religious matter, and not a legal matter.
Some worlds have idiosyncratic views on such matters, which is an item of possibly great concern to those of that world, and a matter of utter indifference to everyone else. Local standards always apply in those cultures.