I've just finished reading The Primal Wound by Nancy Verrier. It's about her belief that separation of the child from the birth mother causes a deep psychological wound, even in cases of adoption, where the adoptee was a baby and has no conscious memory of the events.
She believes adoptees (and any child separated from their birth mother) will experience the event as abandonment. She goes on to explain that this sense and experience of abandonment can affect the development and maintenance of future close relationships (e.g. between the child and adoptive parents, future adult partners, parent and child etc.) and the development of a 'sense of self'. She suggests that having experienced abandonment once, suffers may resist close relationships as a way of protecting themselves against future potential abandonment. That's the theory at least.
I was given up by my birth mother soon after I was born, and finally adopted when I was five. In the intervening period I was in care, and spent a lot of time in hospital. Even after adoption I experienced being repeatedly taken and left at hospitals (for treatment) by my adoptive parents as further abandonment.
I do recognise certain behaviours that can be linked to the experience of abandonment and fear of this happening again, for instance.
I have never been or felt emotionally close to my adoptive parents. Some of this is also about my need to have control of me, because of other aspects of my childhood where I didn't have any control, but I believe it's also because I feared of further abandonment by them, and I have integrated this fear. I deliberately live hundreds of miles away from my parents, so as to keep them at 'arms length'.
I push my own family away emotionally, and sometimes struggle to feel strong emotions towards them. I also do this when I feel they are threatening my autonomy. I also push friends away and am very poor at keeping in touch. Friends have to work hard to maintain a friendship and contact. And yet when I lose friends I am devastated and can't recover from it (as happened a few years ago).
These are some things I recognise about myself that I believe have some roots in abandonment. The book I mentioned has been very helpful in highlighting some of my responses to feelings that are somewhat dysfunctional. Recognising them is at least a starting point in trying to change my dysfunctional behaviours.