Profiles with a link to Wikipedia are compared to the Wikidata item corresponding to the Wikipedia article (I think only when it is confirmed that the linked Wikipedia article corresponds to the profiled person). - this is done automatically, I think on a weekly basis (perhaps less often, but not more) through one of Ales's database tools.
If a profile matched to an entry in the Wikidata database has no connection to the main tree, this triggers DB Suggestion 568, signalling a notable (or close family member of a notable) not connected to the big tree. There are two suggestions, one for unconnected notables with family members attached (unconnected branches) and another for stand-alone notable profiles (unconnected "orphans" - nothing to do with the orphan status of the profile).