Birthmarks generally result from an overgrowth of a structure that is normally present in the skin. For example, an overgrowth of blood vessels produces vascular birthmarks or haemangiomas; an overgrowth of pigment cells produces congenital naevi or moles.

Are birthmarks Genetic?

Are birthmarks genetic? Some birthmarks are hereditary and run in families but most aren't. Very occasionally, some are caused by gene mutations. For example, some babies born with port-wine stains have a rare condition called Klippel-Trenaunay syndrome.

Is birthmarks good or bad?

Birthmarks are usually harmless, but in some cases, they can cause cosmetic issues, grow rapidly, or be a sign of underlying disease. For example, larger moles have a slightly increased risk of becoming cancerous.