My wife and I recently got a dog, and even though we never had any formal training, it seems like she (the dog, not my wife) prefers to urinate outdoors rather than indoors.
When she wants to go, she'd wander around near the door uneasily and whining occasionally, and when I take her out then, she picks a spot immediately and takes care of business. Also, if she's not done, she'd not come inside despite beckoning and tempting with food. When she finally has the last bit of poo/pee out, she'd come inside.
Again, my wife and I got her from some people who didn't train her at all. They just tied her up near the construction site.
It's not a problem or anything, but I'm just curious as to whether dogs, by nature, prefer to poop and pee outside.