about inbreeding and in the link provided.
Inbreeding does not cause mutations. It only passes along already existing ones. The chances of inheriting a negative or positive trait increase with inbreeding because the same genes keep getting passed on to the next generations if both parents carry the same genes because they come from the same ancestors.. Recessive gene traits are the most affected by inbreeding because the chances increase for the children to inherit one recessive gene from each parent.
Regarding hemophilia, Queen Victoria did not have it. She was a carrier if it. It is a sex-linked disorder, carried on the X chromosome. Since women have 2 X chromosomes, they have a chance of inheriting a normal blood clotting gene with one of their X chromosomes, even if they get the hemophilia gene from one of their parents. But men have only one X chromosome, so if they get a hemophilia gene from a parent they will have the disorder. Therefore it is rare for women to have the disorder. Usually they are carriers while the men in their family, especially their male descendants, will be hemophiliacs.
Queen Victoria had a large family. Some of her children married into royal families that were not related, or at least were distantly related, but they passed the gene on to their descendants.
Inbreeding in the past occurred smong common people, too, especially peasants. They lived in small villages with limited choices in marriage partners since they did not travel much except.in times of war. After a few generations, most.people in a region were at least distantly related to each other. That is why certain traits are associated with certain areas.
It happened among middle classes, too, often in order to keep property within a family because the eldest usually inherited the property. If a man who inherited his father's land and.business.married a female cousin, he received a dowery from her and.both families had a stske in the property.
I do not believe that Neanderthals made a conscious decision to mate with their relatives in an attempt to preserve their species. I think they simply mated with who was available and their chouces were limited due to small numbers. I also do not believe that Inbreeding.caused their extinction. There are many possible causes for it -- climate change as glaciers melted, larger numbers of homo sapiens crowding them out, possible diseases carried by homo sapiens, wars with homo sapiens, etc. We know that some of them mated outside of their families to homo sapiens.
Most people alive today have some inbreeding in their family tree somewhere, generally (we hope) in the distant past.
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