I believe the word commonly used is "profiling". For instance, I can't help but notice that the language constructs and manner of posts of one prominent poster on these boards resembles a very high profile poster from years past with whom I gained some familiarity. It has been interesting to backtrack and view the commonality of interests these two seem to have shared.

Coincidence? Yeah, that's it. Just coincidence.

But, the more records we accumulate, the more easily such possible similarities are observed.