My little sister was about 11 when my parents actively stopped being witnessess. She had very limited knowledge of anything JW related as they had been sporadic for several years.
I have to say her friends all through secondary school would of put a lot witnessess to shame. They were good students, didn't under age drink, do drugs or have sex and very rarely sweared. They were/are a lovely bunch of girls even now they are in their early 20's. I think there are plenty of parents out there that manage to instill great moral's and produce well behaved, great kids.
I think you just have to go with your gut feelings about things and as long as you remain consitant in what you feel is right or wrong you can't possibly do a bad job.
I understand where you are coming from as a mother myself, all we can do is what we think is best for our children. You know at the end of the day they will always find fault in their upbringing no matter what you do! lol x