For adoptees, there is an extra layer to this, for it is not only that our lives would have been different but that we ourselves would have been, in a sense, different people. The first juncture, for many adoptees, occurred at or before birth.
I have had many names throughout my life. In my offline life, most people know me as "Becca." When I was a child, people often called me "Becky," and I was too shy to correct them. I've had a variety of nicknames, but I won't mention those here. One name I have never been called is "Georgia." But that is the name that my birth mother would have written on my birth certificate, in honor of a favorite aunt, if she had been allowed to do so. Instead, she was told to leave that part blank and just sign her name.
So, Georgia never really existed, and yet she is a part of me. She is the shadow self, the me I would have been if by some miracle my first mother could have received the support she wanted in order to parent me. I recently saw an old photo of a significant portion of my biological family -- my mother, my grandmother, my aunt and two uncles, my brother and my cousin. My uncle had identified it as one of the rare photos in which "everyone" was present. Everyone, that is, except for me. The photo was taken a few years before our reunion, so I'm not in it. Except that I am; I was always a ghost child in that family. When I look at the shadowy space between my aunt and one uncle in the photo, I see the spot I might have stood.