I have great respect for many biographers and a high regard for a few. But some just didn't do their homework.

Dodgson himself must take some of the blame. His rigorous attempts to protect his privacy and to shun all forms of publicity made successive generations suspect that he had something to hide - some dark secret that if revealed would tarnish his reputation for ever - some dreadful error of judgement that would cause society to shun him - or some awful characteristic that would repel even the most broad-minded of souls. He had a public name but not a public face.
After his death, the custodians of his literary estate did little to release the truth. They followed the social sensitivities of the late Victorian and early Edwardian age - the private life of Lewis Carroll was not for public consumption. His literary legacy fared badly - many of his papers and personal effects were destroyed in the name of haste and expediency, but other motives were in play. Highly important documents were removed from the scope of future research - his 24 volume letter register containing summaries of all correspondence received and sent since 1860, his complete photographic catalogue of all pictures taken from 1856 to 1880, the drafts and proofs of many publications, and parts of his thirteen volume diary.

So biographers are bereft of key primary source material. But to indulge in highly spurious speculation is not the way forward.

Edward Wakeling, 2003.