I read an article, which described someone as contracting haemophilia from his mother who was a carrier of the virus. I thought that haemophilia was a genetic condition? Has something changed?
You are correct. Haemophilia is a genetic condition and is not acquired by a virus.
It is caused by a sex linked recessive gene, which means that half the sons of the female carrier are affected. Only males are affected by haemophilia. Cases vary considerably and some individuals are affected worse than others. There is a high mutation rate of the relevant genes, which can result in a case arising even in the absence of a family history of bleeding disorder. Perhaps this explains the reference to viruses in the article you refer to. I am speculating here but perhaps it was suggesting that a gene mutation occurred in the mother as a result of the influence of a virus. However, the central point remains that male children are born with the condition because they have inherited a particular set of genes.