26 JUNE 1993, Page 30

Blood will out

Sir: Anyone must hesitate to tangle with a professor of genetics on his own patch (`No further room for improvement', 12 June) but how can Steve Jones know that the X chromosome with the haemophiliac gene came to Queen Victoria from her father rather than her mother? It would also be possible that the mutation occurred in one of the chromosomes soon after Victoria's conception.

As for selection, natural or otherwise, this is measured by number of offspring surviving to breed, and can be brought about by differential fertility as well as by the death of the young. Which brings us back to what the two Winston Churchills were worrying about.

Findlay Dunachie

12 Rowallan Gardens, Glasgow