It occurred to me that one of the reasons that teenagers used to watch their diets back when stegosaurii roamed the earth was that everybody knew that greasy foods like chocolate and double-cheese pizza caused acne to break out.
There are now many effective treatments for adolescent acne, including maintenance doses of antibiotics and Isotretinoin. These treatments are so popular that many patients, and their parents, gloss over the fact that some of them increase the risk of suicide by a factor of six.
It also means that teens can gorge on pizza and taquitos dipped in ranch dressing, and other fatty foods without the near-real-time feedback of their face breaking out.
Proving once again that it is not nice to fool Mother Nature.