Biting gerbils

[Kathleen DiMaggio]

Early this past April I had to return two pet shop gerbils that viciously bit
me back to the pet store. They were in a community tank with 3 gerbils that
were the children of two of my breeding pairs....Two gerbils from one pair
and one from another pair. Two of these gerbils (the siblings) also started
biting around the time I returned the pet shop gerbils to the store. Since
these are gerbils from my clan, I wasn't so worried that they could get my
kids or me sick (I'd written Julian when the pet shop gerbils started biting
to find out if they could actually make us ill from a bite)  I've kept my
home bred gerbils and have been trying to tame them. I was worried that the
pet shop gerbils from the unknown source (the pet store) may carry Rat Bite
Fever (is that the correct name Julian?) or who knows what!

I have a few questions:
Why did my home bred gerbils start biting also...did they learn this behavior
from the pet shop gerbils?
I've tried offering gifts of treats to them and they still go to attack
me...what else can I do to tame them?
I've had many gerbils and they have always been very sweet non-biters. One of
the home bred gerbils from this troubled group has remained as nice as ever.
Is he in danger of also acquiring this biting behavior?

Sorry for the long post. I have children and I'm concerned, but I also don't
want to just give up gerbils that were born under my roof for biting
behavior...besides they aren't suitable as pets for just anyone right now.

Kathleen