It doesn't annoy me in the slightest. I am a person, they are a person. If I was chatting or getting to know a stranger (especially if they are a repeat I am seeing), I would ask them personal questions. It's like being stuck on a broken down train or bus next to someone and needing to fill in time - what are you going to do inbetween having sex?
I hate small talk with a passion. I would much rather have a real conversation, if it involves personal details about myself, so be it. I have nothing to hide, I don't see why I should. Neither do they, most people don't have the slightest negative intention - they are there to get their rocks off and there because they like you; they are married and want to go home and keep you as a positive thought and fantasy at most. I can manage creepy weirdos. The job carries a risk, I knew that before going into it. I'm not going to tell them my mothers maiden name, the first street I grew up on, where my sister works, my boyfriends surname and what gym I go to. Clients generally are happy to reveal as much about themselves, people like to talk, I don't see the issue. I go with the flow.