Actually this is one case where "the plural of anecdote is not data" line really doesn't apply. I think you misunderstand what the word "anecdote" means. The definition of "anecdote": Our individual cases are not "anecdotes", each and every one of them is an individual data point. And each case is a data point that contradicts Dr. Dick Swab's hypothesis. "My parents did not smoke, and I am gay"...that's data, not an anecdote.