KIDS-when is it ok for them to know 'grown up' things?

Whenever they ask. We answer all questions - as well as we can, anway

Usually, after a couple of sentences of deep meaning, the really heavy topics give way to talking about Pokemon or what music is in the charts or iPads or computers, whatever the world and beyond has to offer.

Why not talk about sex to a 4-year-old, if he/she asks? There are a couple of really good books to illustrate how mummies and daddies fit together (eg. by Babette Cole). Or would you tell them that babies come from storks?