How are genetic conditions passed on?
Genetic conditions can be passed on from one generation to the next. For example, the blood clotting disorder, haemophilia, appeared in the UK's royal family when Queen Victoria had her children. A DNA mutation probably occurred in the sperm or egg that made her, giving rise to an altered gene. Although she was not affected by the condition herself, she passed haemophilia to one of her sons, and two of her daughters were unaffected carriers of the condition.