TIO

Not true. Strong pectorals will sometimes raise the nipples, and excess fat, as rider suggests, may lower it. Some people are simply born different.
Med students are, therefore, always taught to count ribs down to the fourth intercostal space when listening for heart sounds, rather than assume the nipple corresponds to a particular rib.

Lunchbox is being a bit sensationalistic. Although the gene for porphyria is not uncommon, the vast majority of carriers never exhibit symptoms, and the symptoms he describes are very extreme.

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Strewth