Don't take this harshly, but rats are not hampsters. They are much more intelligent. If the mother rat is accustomed to your smell, then she won't try to kill her babies if they smell like you. I would recomend handling the babies as soon as possible. I've even heard of people handling the baby rats only hours after birth. I still have yet to be bitten by a rat, regardless of age or sex. Good luck with your breeding, keep us posted.