Ethnicity - When I first started playing Sims I made sims that look like me basically. As time went on I started creating and playing sims of all colors even "berry" sims which were possible in TS3. Race and ethnicity don't play into the storylines I create in my head for my sims. They are whatever color they are and it doesn't matter.
Sexuality - My heirs were always straight until Into the Future where the hospital was created that allowed genetically engineered babies. Now they are whatever they seem to be. My nonheirs have always been a mix of straight, gay and bi according to my whim or story progression.
Religion - No religion exists in my sim worlds. In real life, I'm rather anti-religion and that carries over into my game.
Edit/Note: I've answered using TS3 rather than TS4 because more options exist in TS3. CAS in TS4 does a better job of giving options for more ethnic looking sims but you can't create fanciful ones really. I still approach it the same. My sims look like whatever I felt like making them look like with no thought or regard for race or ethnicity. I don't create white, black, Asian, Hispanic, or Native American sims. I just create sims.
