6. Your 3-year-old wants to know if he can have a baby too. You:

A: Laugh at him.
B: Assure him that if he really wants to when he grows up, he can.
C: Tell him no, only mommies can have babies.

Answer: C. It might seem like an adorably cute statement to you, but to a 3-year-old it's no joke. He won't understand why he can't have babies too unless you tell him why.
"This isn't a sex question at all, it's a reproduction question," says Meg Zweiback, associate clinical professor at the University of California, San Francisco School of Nursing. "He wants to know where newborns come from. You can tell him they come from mommies and that he can be a daddy and help make a baby when he's grown-up."
If your little boy feels cheated, that's a cue to sit him down and tell him all the ways a father helps take care of an infant.

7. Your 4-year-old recently discovered he can make his penis get bigger, and he wants to show his new trick to Grandma. You:

A. Acknowledge the wonder of his anatomy -- and explain that he should keep his new trick to himself.
B. Ask Grandma to visit when he's sound asleep.
C. Tell your spouse to deal with it.

Answer: A. It is a neat trick, so don't squelch his innocent enthusiasm by shaming him or getting angry.

"What needs to be said to both boys and girls is 'I know that's fun and feels good, but it's private and should be done in your room by yourself. It isn't okay to share that with others,'" says Sylvia Hacker, associate professor emerita at the Schools of Nursing and Public Health at the University of Michigan in Ann Arbor.

Any self-respecting 4-year-old will then promptly ask, "Why not?" You can tell him it's not polite to do it around other people, or invoke collective behavior ("The rule is you don't touch your penis in front of others"). After all, part of the discussion about sex is teaching young children about what's socially appropriate -- ideally, without conferring any sense of shame along with it.