This shows how history repeats itself in certain situations. In these 3 situations, the story is repeated for the “C” and “A” sons. All 3 times, the “C” son either kills the “A” son, tries to kill the “A” son, or is responsible for the death of the “A” son. This is not the only proof that history repeats itself in this book.
Another example of this is how when either Adam from the bible or Adam from East of Eden is exposed to satanic evil, their eyes are opened to the world around them.