Every one has there own smell, when I was very young and we visited older people the one thing I always remembered is that smell of old people. It though was not the person who I was smelling, it was all the life of collected things and particular items used primarily by elderly.
Babies also have a distinct smell, this also because of the items used particularly used on babies. Young girls and boys smell distinctly different, everyone has a distinct smell depending on their hygiene and items use for hygiene or to cover up the lack of. I believe if anyone no matter the age used the same items and routine for hygiene, they would not smell so different, but each of us still are a bit different in smell simply because of that which we eat or drink daily.
A perfume can smell differently on each person who wears it, one thing that was obvious since my early years is walking into a room after a couple just had sex. Without any reason to suspect so, it was obvious to me the smell of sex was there and those in question smelled the same. Just like those who smoke and do not think others smell it on them.