I would think that it is more common for si to begin in the pre-teen years to early teens when kids are going from the safety of childhood to the uncertainty of finding themselves. Problems seem more devestating at that age. Pre-teens (around 12 yrs), and early teens are learning how to cope with new feelings, independance and figuring out relationships of all kinds. They are particularly volatile and don't shake off teasing or insecurities about themselves easily. Some kids turn this outward, teasing others, starting fights etc, while others turn things inward, becoming isolated, depressed or self destructive. (You'll notice that this is also the age when kids shoot up schools). The coping mechanisms we learn at that age tend to change with age for "normal" kids, but kids on the outer edges get stuck. They continue to use the same coping mechanisms, usually destructive, and can't seem to move on. There may have been a time for a kid when SI seemed to relieve their emotional pain, and perhaps even succeded in an adult noticing their pain and interviening, but the relief was only temporary. Once the kid is an adult, SI may still temporarily relieve emotional pain, but it also becomes a behavior that brings the person shame and is kept secret.

The sad thing is that if an adult had taken the time to aggressively interviene, and get the kid into therapy, some of the people on this forum wouldn't have to come here.

Sam2