well its simply this really . some of the litter will be more like there mom , colouring & temprement & the same goes for the father, to be honest what did you expect them to be like, ''dads temprement & moms colouring, its a lottery as to what you get & obvioulsy in your case it back fired, ferrets arnt any use to any one really if there totally unhandable.
Personally if i bred i would go for temprement rather that showey colouring , just my opinion of course