As adults we forget what could be traumatic for a child. We think we are looking for big events, but really it's anything that was overwhelming. What sticks in the memory are events that engaged all of our senses at the moment of overwhelm. In that instant, it codes into the instinctive memory with deep indelible roots.
Trauma is sensory overwhelm, and sensory overwhelm is violating in impact. It smacks into us. It hits with a high resonant volume. Often, it's things we don't understand.
What was overwhelming and traumatic for one, might be nothing to another. It also depends on what you have already experienced, and how good your sensory system is at sorting and categorizing. If you have a lot of file folders already, then your system knows what it is.
I had a mother tell me that she decided to invite people to 'pet' her stomach when she was pregnant. She invited people in to the space, and felt that the baby was experiencing, in a safe way, lots of different sorts of people's energy. Her child is now a one year old girl, and she likes people. Will this change? It will be interesting to watch. This mother is also a nurse.
She said she didn't try this with her son, who is three, and he has always had more caution around people. Is this a personality thing? AND if so, does the personality start to form in the womb? Why not? If we are experiencing emotion via our mother, why then couldn't we be learning our primitive instinctive survival from her experiences? And why then, couldn't she also be teaching us?
Since the emotional in-utero experience codes into us, why can't we teach the growing fetus, in a conscious way? I love this idea.
On the same note, I have another mother who has recently given birth to twins, and she has completely kept them isolated from the public even now and they are 8 weeks old. For two months they have been exposed to only the immediate family and caregivers she has carefully screened.