As someone who is quite unfamiliar with your religion, I am curious as to why the Unitarian Universalists are relatively homogeneous and educated. Is the recruitment passive? Are there some kind of special requirements to join? I'd highly appreciate your insight.

According to this study, Unitarian Universalists are older than the US on average. 62% percent are women. They are 88% White, with Blacks and Asians coming in around 1% each, while Latinos make up 4%, and "Other/Mixed" account for 7%. The vast majority are not recent immigrants and have been in the US for more than 3 generations. A plurality of Unitarians have a household income of 100k and above. They are also highly educated and strongly liberal, 84% identify as Democrat.