status and the age of the person. The genes primarily determine the amount, patterns and thickness of chest hair. Some men are very hairy, while others have no chest hair at all. All ranges and patterns of hair growth are normal. The areas where terminal hair may grow are the periareolar areas (nipples), the centre and sides of the chest and the clavicle collarbone.

The direction of growth of hair can make for interesting patterns, akin to depictions of mathematical vector fields.