Although there is a small but significant body of research comparing same-sex and mixed-sex relationships and sexuality, there is virtually no research that takes into account the incredible range of relationship types in the LGBTQ couples—what is the “relationship type” of a genderqueer person and a lesbian, for example? In particular, it would be useful to develop a body of knowledge about, for example, relationships that include more than two partners, relationships where one or more participants are transgender, and relationships that are founded more on dominance/submission dynamics than on gender. In the absence of such research, this entry will confine itself to findings on same-sex couples, male or female.

Philip Blumstein and Pepper Schwartz conducted pioneering research comparing same-sex female, same-sex male, and mixed-sex unmarried ...