Great Video, Silver. I believe the word of God to be perfect and true, so I see things like this in the most simple of explanations. God created only 2 people, and later, only 2 cows. The Genetic defects, or as I prefer, Genetic mistakes created all the differeences. Of course, the more closely related, the greater the mistakes. The further apart the realtion, the greater the number of variables. So, to answer your question, Yes, the tendencies in calves will be mostly determined by the Sire and Dam, but those mistakes happen in EVERY calf.
Here is a website that will show how quickly genetic make-up can change. Start at Page 346, and this should help make sense of what I said.http://books.google.com/books?id=wL2gZwf9px4C&pg=PA359&lpg=PA359&dq=genetics+chart+Aa+Bb&source=bl&ots=QO5NE75yvf&sig=hCGxOMsmDYpd6uyqX-lIi0aOlko&hl=en&ei=iYzeTMzTI4K8lQf6zvWpAw&sa=X&oi=book_result&ct=result&resnum=6&ved=0CC0Q6AEwBQ#v=onepage&q&f=false