https://www.ncbi.nlm.nih.gov/books/NBK219218/
I don't know. I found this article of interest. It's lengthy and contains several theories.
How did her parents handle that incident that happened at the age of 7? Was she placed into counseling at that point?
What are your theories as to what could have brought about this stunt in her developmemt? And how are her parents protecting the 3 year old from all of this inappropriate touching?