Fact: Everyone's skin is fundamentally the same
I can hear your screams of protest to this statement already, but just hear me out …
The basic structure of everyone’s skin is the same.
However, just like some people have diabetes mellitus and others have dodgy knees, lots of people have a huge variety of skin problems.
The more accurate thing to say is: everyone has different skin problems, different personal preferences and different expectations of treatments and products. Some people don’t have any skin problems at all (or they don’t really care either way and that’s totally fine). If a moisturiser ‘works’ for one person but doesn’t for another, it’s because they have differing skin problems that require different management, different personal preferences or different expectations of that moisturiser. But it’s not because their basic skin structure is different; every human has a dermis and an epidermis composed of the same types of cells and molecules. What that means is that ‘active ingredient X’ which supposedly, for example, improves pigmentation, should improve pigmentation in every single person who has the same type of pigmentation problem (for example, melasma).