I've seen this answer, where the person says that one might present oneself poorly if they hide their personal lives from their co-workers.
In-spite of that, I believe that revealing information about one's family can create prejudices in co-workers minds. This, apart from people wanting to form gang's/groups where the accept or reject people based on their country of origin or the language they speak, and basically create office politics.
Be it something serious like office politics or something minor like a prejudice or a coloured opinion because they know something about your personal life, these are the questions I have:
If a person wants to be known to their colleagues on the basis of their professional skills and manners, and not on the basis of their personal life, then is it appropriate to politely decline to answer personal questions? (so are you married? How many kids do you have? What Did your Dad work as? What did you do during the weekend? How old are you?)
If one could politely decline (while on probation or as a confirmed employee), how would one do so?
Will declining to answer such questions really seriously hurt professional relationship building between colleagues? Any negative or positive side-effects it might have? Aren't we better off focussing on our jobs? If we do get along with colleagues well, then wouldn't outside-office-hours be ok for personal questions and socializing?
Does declining, have a different effect/repercussion in a startup, mid-size company and large size company?
UPDATE1: This does not mean that the person wouldn't want to talk to colleagues at all. It's about wanting to be with them and talk about technology and what's happening around the world (and trying to be diplomatic and politically correct all the while), but not giving out info about one's personal life and family. Not because there's anything to hide, but in order to prevent certain prejudiced opinions or uncomfortable follow-up questions.
UPDATE2: Ok, so it's more advisable to give a vague answer or deflect it rather than explicitly decline from speaking about it. I'll say that's an art that needs to be practiced, but well worth it, because this art also helps in deflecting/defusing conflict situations. Thanks everyone! :-)