Comments by "Andrew Brendan" (@andrewbrendan1579) on "The Queen Mother Explains the Hereditary Principle | The Crown (Helena Bonham Carter, Marion Bailey)" video.

@Dr.Yalex103 Along with the issue of the inbreeding there was and maybe still is the issue of hemophilia among royal families. To the best of my understanding and recollection, Queen Victoria carried the gene for hemophilia which was passed to her daughters who married into other royal families of other branches of the same royal family and where the condition manifested itself in males. The author of a book I read about Victoria's daughters said the hemophilia spread like "wildfire" among royal families. I believe the hemophilia gene in Victoria was simply an anomaly rather than the result of inbreeding.
1