LIAR! LIAR! Pants on fire!

Here is the question -
How can a teacher combat against children's negative habits/behaviors that are learned from his/her parents?

True story -
A Visa Gift Card was "lost" in my house.  I had received the gift card from my 2nd grade team to purchase wall art for my baby's nursery.  Upon calling customer service to receive a new card, it was found out that the card had been activated and spent in 3 locations in one small city.  This one small city is coincidentally the same city that my nanny-friend lives in.  My nanny-friend and parents are the only people who live in this one small city that come to our house.  When accused, my nanny-friend denied stealing the card or anything from us.  Upon further research into the spending of the card, it was found that the items purchased at a store were purchased with two cards - one matching the gift card numbers and the other matching the debit card numbers of my nanny-friend.  The items purchased were seen in her bathroom, on her toenails, and food that was at her son's birthday party two days after the purchases were made.  With the new "evidence" found, I confronted my nanny-friend.  I was not asking for the money back.  I simply wanted her to admit to taking the card from our house.  My nanny-friend, with all the "evidence" in front of her, still denied taking the gift card.  It was actually stated, "I did not realize I took the card . . . I don't remember paying with two cards then . . . I did not take any money from you."

Here is the connection -
It cannot be denied that my nanny-friend is lying.  There is receipt proof that she used the exact gift card with another one of her cards to purchase items that are seen on her and in her house.  This situation started my brain rolling on the fact that I trusted this person with the care of my young children at my house as a good friend and child-care provider.  It then came to my mind the times that her own son has lied, while playing with my son.  I have also heard my nanny-friend refer to her own mother as a liar.  My mind went to further wondering about personality traits of people that are "passed down" from our parents.  It is said that personality traits, like lying, can be passed on to our children.  It is a learned behavior that can be learned from people the children are around frequently (as stated in an article from www.notmykid.org found July, 2011).  As teachers, we see many instances of children lying to us and their peers in our classrooms.

Here is my reflection -
How, as teachers, do we combat against this negative personality trait?  How do we change the negative behaviors to better our society when the behavior is ingrained and seen frequently at home?  We only see the children approximately seven hours a day, five days a week.  If lying has become a habit, how many times does a person need to correct the behavior to permanently change it?  Yes, as teachers we are better examples in front of our children in the classroom.  Is that enough?  What else can we do to combat the negative influences that some parents have on the children coming into our classrooms?

 Harry Chapin sings,
"I'm gonna be like you dad.
You know I'm gonna be like you."
(lyrics from The Cat's in the Cradle, 1974)