Difficult Discussion

YankeeGran, I think perhaps an approach that starts from the point of view of his welfare might be the way to go. Suggesting that he will have problems making and keeping friends or might lead to him being teased and/or bullied.
Another thing has occurred to be, I might be well off the mark and I apologise if this offends but, if he is so pre-occupied by this behaviour might he have been introduced to it by someone else? I have no experience of such things but in my early years training we were taught that inappropriate attitudes to sexual behaviour (taken as part of a wider picture including signs of withdrawl and challenging behaviour) might be indicative of something else.
Do have that chat with your daughter, emphasise that all you want is this little boy to grow up happy and content. All the best.

Thank you for all your comments. My daughter and I are having a spa day together in a couple of weeks. I'm thinking of trying to raise the subject with her in this relaxed atmosphere but I'm just very nervous about what to say. Maybe I should send her a version of my opening comments (here) as these might be more neutral than anything I would say might sound.

Professional help definitely. A seven year old should know what is right and wrong in most areas of life: i.e. we don't steal, we don't hurt animals etc etc so if he has not taken on board what is acceptable in this area by now there needs to be another approach.

I would definitely suggest his parents seek help. He could get info a lot of trouble if this behaviour is not controlled.

It might be easier for someone other than parents to talk to him about this. It is a very sensitive issue and if a parent does not feel really comfortable with how to tackle this they could make things worse.

Help from someone with proper experience might make a much better job.

I encountered a school having to deal with a situation like this where the lad was causing upset and annoyance to the other boys. This lad was ostracised by because of this behaviour which was upsetting for him.

Just read this again and the bit I put in about 7 year olds has disappeared. The second para should begin 'It's usual for teenage boys to find themselves in a state of arousal at inonvenent times (and it's not uncommon for 7 year old children, too)........'

YankeeGran he needs some guidance to gain control of this behaviour pdq before he gets into trouble. His parents can help him to understand the boundaries to dealing with his sexual feelings, and that masturbation in private is normal, but not when involving or thinking about children much younger than him. If they need help, first port of call is the GP, who might not have expertise in dealing with this behaviour, but will know someone who does. He can learn to distract himself by involving himself in activities like physically challenging exercise that does not require close contact with children, developing interests that he can focus on instead of indulging in unmanageable sexual feelings.

It's usual for teenage boys to find themselves in a state of arousal at inconvenient times, but not to use this to involve younger children, and giving him this information in a sensitve way that doesn't embarrass him will help. So many adults who look back on their developing sexual interest in children mention how uncomfortable in their sexuality they were around adults who made them feel ashamed. That's just one small aspect of it, though - being abused and corrupted by others, watching deviant videos, lacking adult support and guidance all play their part in a complex issue that can be curtailed with early, meaningful intervention.

Please don't treat him as though he has a horrendous problem - in all likelihood, some sensitive guidance and a bit of attention to keep him otherwise occupied will help to extinguish this before it develops.