Elevated Psychiatric Risk in Same-Sex Married Individuals: Large-scale Evidence is Consistent with a Substantial Role of Familial Common Causes

Abstract

Xu et al. present a study of practically the whole Swedish-born population over the age of 25, in which they report an elevated risk in same-sex (compared to opposite-sex) married individuals of depression, substance abuse, and attempted or completed suicide. This elevated psychiatric risk is substantially reduced when same-sex married individuals are compared with their opposite-sex married siblings, which is consistent with a substantial role of familial (e.g., genetic and shared environmental) common causes of both same-sex orientation and psychiatric risk. I discuss the study’s strengths, including its huge, comprehensive sample and its use of objective measures, which avoid some of the potential biases in other studies. I also discuss the study’s limitations and argue that the authors misinterpret the role of shared familial influences as accounting for a “small proportion (less than 20%)” of the elevated psychiatric risk in same-sex married individuals. The proportion shown by their results is much larger than the authors report, and even these larger values are best understood as lower bounds in terms of what could be accounted for by familial common causes. Lastly, I discuss future directions for research aiming to understand elevated psychiatric risk in lesbian, gay, and bisexual individuals.