I've often found in my games that long term characters and NPC's autonomously generate many gay and lesbian couples usually becoming pregnant or already with children. It's done I suppose because I like filling up the neighborhoods with the tons of awesome choices from the gallery of all the different homes/lots so the game will often come in and put sims in them before I do when I go back to do any customizations I would like.
I have to be honest I get a lot of diversity from different ethnic groups from across the world represented too, to my delight! My long term favorite save started right off the bat with Don Lothario autonomously moving in with his alien boyfriend who became pregnant from his alien abduction?! :D So I'm wondering if that may be due to MCCC that I will not play without. I never fooled around with tweeking the settings that are pre-set with MCCC so I'm just wondering if anyone else has any opinion about that?