This just came into my mind. Personally, half the time when I'm answering questions I don't know who's the asker unless someone comments on my opinion later on. Well, unless I'm too bored and answer questions from topic then I'll know who's the QA.
Subconciously I do check who QA is because I do make more of an effort with people I know and am friendly with. Then I see if question interests me. On reflection I do check QA's gender , age and if I know them well where they are from and their personality so then I can tailor my answer to their needs say for example a teen starting work, no point in me banging on about what work is like after 20 years experience.