Haemophilia A and B are both X-chromosome mutations, so a sufferer necessarily inherits the disease from his mother. She won't have serious symptoms unless both of her X chromosomes have the mutation, which is very rare. Since sons of a sufferer necessarily inherit his Y chromosome, they can't inherit the disease from him.
I'm trying to find out when it was understood that sons of a sufferer could not inherit the disease from their fathers. The relationship between chromosomes and heredity was clearly demonstrated in 1915. The idea that females were usually carriers and sufferers usually male had been understood since 1813. The XY sex-determination system was discovered in 1905.
However, it is not clear to me when this would all have been put together and become part of normal biology and medical courses. I think the crucial points are:
- There are sex-linked genetic conditions.
- Haemophilia is one of them, and is an X-chromosome recessive condition.
- Men are XY, women are XX.
Can anyone help with when all of that became normal knowledge for doctors and biologists?
Titles and authors of biology textbooks from the 1920s to 1945 would help, since I'm quite prepared to seek out old books, if I know what to hunt for.