Yes I wanna support Zoe's point there.  Just be axtra careful as this topic might now be read by 12 year olds.  Its ok to teach them about sex (the birds and the bees etc) but if you wanna talk about an abnormal kind, make sure that it is discussed as mature adults.  I dont know how but just be mindful....we already have enough underage sex related problems in the country.

Just my 2 cents.