How do U trace a family ?

Question:

How do U trace a family ?

I am trying to trace a family....i have names and last known address although this is 30+ yrs ago. Is there a way of tracing all or some of the family members ? I know for example that one of the family had a child in the late 60's early 70's (and this child may have been adopted/fostered).
However, the hospital where the child was born I am told no longer exists......are registrars obliged to give out information about births even if it does not relate to your own family.
Any ideas about how to begin would be much apprecited!!!

Best Answer - Chosen by Asker: Try the IRS they will can give you all the records they have for anyone you looking for that has been dead for over 20 years.
You could get a hold of the nieghbors of those adresses, if you can't contact them on those.

If the one was adopted out they may be looking for their birth family which will increase your chances of finding them.