I’m not sure, but early childhood infections were the causes of these two women’s sensory deficits, and female infants and children are generally stronger - constitutionally speaking - than boys. It’s possible that these infections would simply have killed their victims, had they been boys.
Or, post-infection, boys may not have been nurtured the same way “fragile females” were. Without the very close - emotionally and physically - relationship with her teacher, it’s unlikely Helen would have learned. I mean, she’s got to have her whole hand smashed all over Miss Sullivan’s face and throat to feel her speak. Perhaps a boy who was deaf and blind would have been left to his own devices more - encouraged to whittle wood instead of connect with people.
Girls also have quicker language acquisition, on average, than boys. Remember that neither of these girls was deaf at birth. Laura was 3 when she lost her hearing and sight - she was probably speaking in sentences before that point and essentially re-learned what was already somewhere in her neurons. Helen became deaf at 19 months - she spoke some words before that, and had her language processing centers pretty well developed to receptive speech. She forgot how to speak, but she did know, at one time. A boy at 19 months might have had less language already in place, making it even harder for him to learn it.
It’s also possible that it’s not a real medical difference, but a public relations one. In the late 1800’s, it was still pretty remarkable for ANY woman to be college educated. The fact that Helen was also blind and deaf just made for extra special headlines. The newspapers may not have been so interested in the story of men in similar situations, if there were any. Add the play and movie in the picture, and it’s not surprising that Helen Keller is the name we all know and associate immediately with deafblindness. That doesn’t mean there aren’t others we don’t name our elementary schools* after. Certainly there *have *been deafblind men of prominence -Bob Smithdas is one; he lost his sight and hearing to cerebrospinal meningitis at age 4. He also temporarily lost his language, and recovered it using techniques like Miss Sullivan used with Helen.
And finally, we’re talking about a sample of four women mentioned in the thread so far. That might be simply statistically insignificant, and there may be actually no difference at all in prognosis for boys or girls. Wikipediahas a list of prominent deafblind people, and it does include men and women, but frankly I’m too lazy to look them all up and find out at what age they became deafblind and if they lost/regained spoken language or not.
*I actually attended Helen Keller Elementary school. It was kind of awesome, because when we went on field trips, many places assumed we were all blind or deaf, which meant we got the best seats at the theater, extra attention at the museums and whatnot.