Persian
Your post is in no way offensive, but this comment:
Seriously, don't see what the issue is with adoption - it's normal. Friends in our primary were adopted, nothing thought of it other than initial interest
Was made around the time that it was pointed out that adopted children shouldn't be identified to other parents classmates in order to prevent teasing. It was implied that 'all children' are teased in the playground at some stage about something and that this was simply another of those reasons.
Anyone who understands a little about child development would understand this simply isn't the case.
In the first 12-24 months of a child's life, they are making secure attachments that will provide the base for a huge number of things - self-esteem, self-worth, how they perceive the world as a whole.
Think of a child in a typical family. The child gets hungry or wet. The child cries. The primary caregiver rushes over, comforts the child, then meets their need (food, nappy change). The child learns, at a very basic level, that the world is a safe place, they are important enough to have their needs met and as a result, they develop self-esteem and resilience. They lay the foundation for understanding that if they get told off (I'm talking years later), it is the behaviour that is bad, not the person. They feel guilt, but still safe.
As you rightly identify, almost all children who are adopted or fostered have not had this type of upbringing. Likely their needs were NOT met in their first few months. Or worse still, crying didn't bring comfort and relief, it brought an unpredictable or violent adult.
These children do NOT form a secure attachment. They fear the world and learn that they are not important. They are less likely to be able to form emotional resilience.
Crucially, their internal working model tends to be not 'I behaved badly' but 'I am bad'. They don't feel guilt - they feel shame.
THAT is why there is a HUGE difference between 'normal' playground teasing and how an adopted child may feel if someone tells them 'you don't even know where your real Mum is' (as has happened to my DS). And it's why it's important to protect Looked After Children's privacy, not splash their status around for all to see/comment on without understanding the impact.
If you're interested, Bowlby did a lot of work on attachment theory many years ago. It's fascinating (and heart rending at the same time).