Today Oprah's whole show was about having the sex talk with your child- starting at pre teen years. A third of the show was about "self pleasure." The theory being that if the teenage kids have this outlet it may help them through the 'hormonal' periods.
It is my understanding that Islam forbids the "m- word'.
In the world of advice of "it's ok, it's normal, nothing wrong with it, not hurting others." etc. When your daughter/son asks what is wrong with doing it, other than dogma- what do parents say?