"Violence of temper approaching to mania has been hereditary in the men of the family," Miss Stoner says of her stepfather's family. Do you think Dr. Roylott gave evidence of having inherited this trait?

Dr. Roylott certainly gives plenty of evidence of possessing violence of temper approaching to mania, but the only evidence that it might be inherited is Helen Stoner's assertion. She must know a lot more about Roylott and his ancestors than she tells Holmes and Watson in her back story. A modern reader might feel skeptical about her belief that her stepfather could have inherited his violence of temper from the men of his family. But we must remember that people in the Victorian era knew less about such matters than is known today. There were undoubtedly a lot of false theories about human psychology and genetics in vogue at the time which have since been discredited. Sir Arthur Conan Doyle's purpose in having Helen offer this diagnosis of her stepfather's violent temper is most likely to offer some explanation for it, however speculative. It tends to make his character more credible. Helen's explanation of Roylott's near-mania sounds somewhat "Victorian"--but this is a Victorian tale written in 1892 and set in Victorian England.