Tolkien even mentioned this in the trilogy itself. "Bilbo and Frodo as bachelors were very exceptional." I'm reading an Op-Ed in the Wall St Journal, a book review of "Nabokov's Favorite Word Is Mauve" by Ben Blatt. It's about what can be done with computers to count up every word an author uses, and the patience to wade thru the resulting mountains of histograms. Apparently they were able to resolve who wrote which of the Federalist Papers by looking at the frequency of the word "whilst" versus that of "while". Hamilton always wrote "while" where Madison always wrote "whilst. Good interesting stuff but I would never have the patience to sort all this out.
Then the reviewer mentions that Tolkien used "he" 1900 times and the word "she" just once when he refers to Mrs. Bilbo Baggins. The first part I can believe, Tolkien's protagonists were all guys, no chicks in the fellowship of the ring. But Mrs Bilbo Baggins? No way, Bilbo never married, Frodo was NOT Bilbo's son, he was a nephew.
Talk about blowing your credibility in one short sentence.