K.W.
This is hard to answer without knowing how old your kids are.
For younger kids, it is usually better to just answer questions they have. Make sure your kids know they can ask you questions. Reading a few "where do babies come from?' type books together may open the doors.
For older kids, have a few books around that reflect your values for them to read. Make sure they are in a location where they can read them without admitting to you that they're reading them. Do your best to keep communication lines open. Grab "teachable moments" whenever you see an opportunity.
I'm not sure I can give you specific recommendations for books unless I know how old your kids are and something about your values around human sexuality.