I would have no problem with a 8-10 or so year old had a relationship with an older person.
However ONLY if the child was mentally matured enough to understand. I imagine most are not. This ain't that they derive pleasure.. this is that they understand what a relationship is and want to commence one. I don't think I have yet meet one person that young who understood those things... but then again.. I tend not to "hang" wiht people that much younger then me... wonder if I have some prejudice there.. perhaps.
