This may be an odd question.....I posted in parenting but think this page may work better as he is adopted.
My son (10) has until very recently been oblivious to smells. Onions chopped, dogs doing smelly farts, manure spread on fields outside etc, he'd never mention it.
Now he does and is very tuned in to smells.
Got me wondering if it's a developmental thing? Or maybe he's just unique