When an anonymous mom asked what are the signs of child molestation (sexual abuse), it got me thinking about all the women I know who were molested as girls. All the men I know who were molested as boys. Child molestation is so insidious; its victims are affected for life--and often carry their "secret" with them throughout adulthood. Talk to your children about the reality--every adult is not to be trusted, and if any adult ever makes them feel uncomfortable or asks them to do something they don't want to--they should say "no!" and tell you immediately.
Here is a list of some of the most common signs of child molestation (of course, individually they may not point to that, but in all cases trust your instinct) :
If a child tells you that they have been sexually abused in any way, believe them. Children rarely lie about sexual abuse and 80% of all child molestation cases involve someone the child knows.
It is NEVER a child's fault.
If you have been a victim of sexual abuse yourself, it might be helpful to join one of the private groups on CM like Overcoming Sexual Abuse (which amazingly has nearly 600 members).
Pens, pencils, markers, etc.