Yeah I second what Cat said. Taboo/Incest/shock factor clients are quite common on cam. If its not something you advertise just smile sweetly 'ok then' and disconnect and ban them. Dont give them the satisfaction of knowing they've riled you. Easier said than done I know!
Or play along and make some money off them.
Just remember the webcam world is fantasist land and try and take everything with a pinch of salt. Having said that I'd be just as freaked as you probably! Must be stressful for you!
As for showing face on cam yeah you've got to really if you want to make decent money rather than a top up of your escort money. (Unless you can work it into your shows as part of a roleplay fetish etc) Being recognised is therefore an occupational hazard, but is less likely if you don't do freeview and only paying customers can see you. I dont show my face straight away so the cheapskate looky loos who pop in and out of your room don't get what they want!
Ive never been recognised yet (as far as I know) by someone but do wear a shit ton of make up on cam and never wear make up in real life, mainly just mud as I'm a country girl!!