Telling any lies at ALL leads to 'keeping secrets' - and that is the foundation upon which child-molesters build their awful edifice of lies and guilt - they say to the child "this is OUR little secret, remember" - and if you have allowed your children to tell lies, to keep secrets, even little 'white' lies, your child is a target. For your children's safety, you need to set and keep just one rule.
No lies.
Ever.
Scott D is absolutely correct.