>>13513166The best I can offer the layman is to understand that genetic recombination is not like a smoothly shuffled deck of cards; rather it is shuffled in chunks. Magicians use this aspect of card shuffling to make sure they have a specific card or sequence in hand. Biology just goes about this randomly. In respect to pigmentation of a feature, you might get 100% of the genetics from one parent, or 0%, with most cases falling in-between. You would have to be very lucky that this specific chunk was transferred, whole, that in reality it never happens. Any specific chunk (a stretch of genes on a chromosome) just gets chopped up, diluted, until any resemblance to the 1st configuration is gone.
This is one reason that, after several generations, you can have an ancestor that contributed nothing to your genetics. The trend is toward complete dilution, not concentration. If you have a chance of 0.5 of inheriting some sequential DNA, your progeny's chance is 0.5*0.5=0.25.
Think about the fact that after 10 generations you have 1,024 ancestors. That is a contribution of 0.5^10 or 0.097% of a genome. That fraction of a percent are by this time chopped up and mere pieces sprinkled here and there. After 20 generations, with 1,048,576 ancestors, it is 1000 times worse, 0.000095%. In the first case, the chance you have a specific chunk of DNA 100% homologous with the individual in generation 10 is astonishingly small. Maybe detectable by analysis. At 20 generations, forget it.
So when someone uses whole fractions with respect to genetics, like "1/4" I know immediately they don't know anything apart from ancestry.
People who claim some specific inheritance from a story about their history are just cherry picking and because of the above, probably 100% wrong in even possessing any genetics from the specified "ancestor". Those contributions were uninherited, chopped up, split a hundred ways, etc.
