Wombtwin symdrome... is it real?

Is there such a thing as wombtwin symdrome?

I read that losing a twin in the womb-- even for kids who never knew they were once a twin (in uterus)-- can cause all sorts of things, from a feeling of sadness, lack of trust, autism, sensitive emotions, starving yourself of food/sleep/relationships, and a variety of things. I find that hard to believe.

Is there really wombtwin syndrome?