Hello Richard. If you go back and reread the post by Eric, you will see that he says that only purists would say that offspring of the same parents (siblings) need be bred to each other to continue beyond the F1 generation. I would go one step further and say that that strict interpretation applies to PLANTS not animals. This whole F1, F2, etc. business was first used to describe plant genetics and trait inheritance, not animal genetics. As later applied to animals, the definition of F1 would be:



"The first filial generation, produced by crossing two parental lines."



The definition of F2 would be:



"The second filial generation, produced by crossing two parental lines from the F1 generation."



And so on, down the line. I hope this makes it more clear. If you go back through this thread after reading the above and read just the other posts I added, it may seem more coherent and less confusing.

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