Hello, I'm a specialist in genetics and biology. Let's dive into the topic of birthmarks.

Birthmarks are generally not considered to be hereditary in the traditional sense. They are congenital, meaning they are present at birth, and are caused by a variety of factors. Some birthmarks are due to an overgrowth of blood vessels, while others are caused by an excess of pigmentation in the skin.

However, there are certain conditions that are associated with an increased likelihood of having birthmarks. For example, Sturge-Weber syndrome and Klippel-Trenaunay syndrome are conditions that can cause vascular birthmarks. If a family has a history of these conditions, there may be a higher chance of a child having a birthmark. But it's important to note that these are not direct genetic causes of birthmarks themselves but rather conditions that are associated with them.

In summary, while birthmarks are not typically inherited in the way that traits like eye color or blood type are, there can be a familial predisposition to certain types of birthmarks when specific medical conditions are present.

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The occurrence of birthmarks may be inherited. Some marks may be similar to marks on other family members, but most are not. Red birthmarks are caused by an overgrowth of blood vessels. Blue or brown birthmarks are caused by pigment cells (melanocytes).read more >>