- May 2014
MY answer to this question: Why couldn't bastards inherit titles? lists a large number of European monarchs who were of Illegitimate birth, and monarchs who were accused of being illegitimate, and cases were persons were barred from inheriting thrones because they were allegedly illegitimate, and attempts to make illegitimate children heirs to thrones, etc., etc. All except the first four were after AD 1000. The latest person of illegitimate birth to become the legal heir to a European throne was born as recently as 1898.
BTW, do you know of any royal claimants (as in, after the relevant monarchy was abolished) who made their illegitimate child their heir?