My dd's birthmother refused to hold or see her from birth, and dd spent 12 days in a child protective services nursery of the hospital she was born in--with a paci and swing regularly. It was a high poverty, high crime city (literally an entourage followed someone into the ER to shoot them AGAIN in the hospital to be sure they died ) and yet when I went to see her at the nursery (she was 8 days old) the nurse there told me "They know when they're not wanted". It sent a chill up my spine--it was such a busy, cold place and that was such a very "connected" thing. I blew her off, but it stuck with me. Dd's bm didn't want to name her, either.
Much later, *I* felt an incredible sense of loss when I connected the dots with her very serious fears: not only had she been "rejected" by her birth mom (and I don't mean because she was given up--but because bm wouldn't look at,hold or name her) but she was a vacuum-assisted birth that was so traumatic that she suffered a sub-galeal hematoma a full 3 weeks post-birth (which is very uncommon).
My dd came to us at 12 days old. She has been both soy and dairy free all but the first 4-ish weeks of her life. She will be 4yo in early November. And she still suffers significant problems with being away from me or my dh, and if one of us is away overnight--she talks about it for weeks if not months. She clearly has some significant underlying insecurities. We cater to them as much as humanly possible and hope that we can assure her enough over time that they subside--but it definitely concerns me. And really, we were pretty oblivious about it for the first couple of years.
There were other things that kind of "alerted" us to her feelings of loss. She definitely noticed the change in language (her bm was immigrant Hispanic and dd would go dead silent when Spanish was spoken around her) and we had two incidents during that "separation anxiety" age where she wouldn't go to ANYone, but she DID willingly allow two Hispanic women to hold her without putting up a fight (they happened to be the same nationality as her bm and dh and I semi-joked that "she knew her people" but never in her presence and it wasn't really funny). She started really studying our faces about that time and it made me panic. In the last 2-3 months, she's been on a tangent about being "brown" and noting that me, dh and ds are not. We were at a pool and she saw some AA kids and asked if she was "brown like them".
So mine is clearly experiencing loss, but also a disconnectedness that breaks my heart. All we can do is love her through it and pray that it fills the void.