Well, the marked ferrets are probably more likely to come from pet
stock than some of the others.  Pet stock ferrets, ****no matter what
the markings**** could be more likely to be bred from generations of
cuddlers, depending on the temperament choices of the breeder than
those not bred for cuddling as a primary choice.  (There was a similar
temperament problem here decades ago when a number of the ferrets sold
were from fur stock; those also tended to have impaired health and
longevity, BTW.  Sometimes when the primary "use" being bred for is
not related to temperament then personalities can be -- let's say --
non-cuddly the same as for anything else not bred for that aspect of
temperament.  Alternatively, when the primary focus of breeding is
appearance instead of health or longevity then both of those can be
sorely impacted in bad ways.)
 
Those sorts of marking, though, are way too likely to be associated
with a number of health and longevity problems.  Here is a post from
a genetics professor which can get you started on these neural crest
genetic variations, and what are those kinds of markings and what are
not:
 
http://ferrethealth.org/archive/browse.php?msg=YG3069
 
You can find a lot more in the archives of
http://groups.yahoo.com/group/Ferret-Genetics/
 
-- Sukie (not a vet, and not speaking for any of the below in my
private posts)
Recommended health resources to help ferrets and the people who love
them:
Ferret Health List
http://www.smartgroups.com/groups/ferrethealth
FHL Archives
http://ferrethealth.org/archive/
AFIP Ferret Pathology
http://www.afip.org/ferrets/index.html
Miamiferrets
http://www.miamiferret.org/fhc/
International Ferret Congress Critical References
http://www.ferretcongress.org
[Posted in FML issue 5222]