Young children want their parents to discuss difficult subjects with them. However, our kids will look to us for answers only if they feel we will be open to their questions. It's up to us to create the kind of atmosphere in which our children can ask any questions -- on any subject -- freely and without fear of consequence.
How do you create such an atmosphere? By being encouraging, supportive and positive. For example, if your child asks, "How many people have AIDS?" try not to answer with, "I don't know. Please just finish your lunch." No matter how busy you are respond with something like, "That's an interesting question, but I'm not sure. Let's go look it up." (FYI: Don't worry that if your children learn that you don't know everything, they won't look up to you. That's simply not true. Kids accept, "I don't know," and "let's go find out," and they are better responses than any inaccurate or misleading answers you may be tempted to offer.) One more point: You don't need to answer all of your children's questions immediately. If your 10-year-old asks, "Mom, what's a condom?" while you're negotiating a tricky turn in rush-hour traffic, it's perfectly okay for you to say something like, "That's an important question. But with all this traffic, I can't explain right now. Let's talk later, after dinner." And make sure you do.