email addresses and even more, real addresses, I can understand people being chary about that.

But birth dates? I suppose you might have a Mudcat Birthday thread, but otherwise I can't see the problem. There probably is one, I just haven't thought about it enough - I know Joe Offer advises against giving birthdates.

But of course there's no reason to give any information you don't want. No need even have to give a recognisable picture of yourself, stick a disguise on, for instance. But it's fun to have something to fill in the imaginary space we share.