Start with freebase.

But you're going to have a serious problem with missing data. Date of parent's death will only be there (in structured form) if the parent is themselves notable enough to have a wikipedia article. Otherwise, it'll only be in the text.

So I think you'll only get a meaningful result if you manually clean the data. Choose a 'neutral' source of notable people (e.g. Who's Who). Hire somebody via odesk or mechanical turk to find and record age of father's death. Compare with averages across the entire population.

Basic manual research is now cheap; take advantage of it!