This is what really causes birthmarks

Birthmarks are fascinating things. According to BabyCenter, over 80 percent of babies are either born with a birthmark or develop one in their first few months. What causes a baby to have a birthmark?

Birthmarks are common, but they're also kind of a mystery. Science doesn't actually know the full truth about birthmarks. It's known that vascular birthmarks, which are typically red, purple or pink are caused by "abnormal blood vessels in or under the skin," while pigmented birthmarks, which are typically tan or brown, are caused by "clusters of pigment cells" (via NHS).

There are a few theories about what causes birthmarks

While we know what gives birthmarks their color, we don't know what causes the abnormal blood vessels or clusters of pigment cells to form, although there are a few theories.

According to the book Diseases and Disorders, there is research that suggests certain circumstances such as being born premature, multiple births, and the use of fertility drugs are linked to the development of birthmarks. 

A 2007 study published in Pediatric Dermatology (via Science Daily) found that some birthmarks might be caused by babies getting less oxygen in the womb. 

Another theory, according to Medical News Today, is that birthmarks are caused by bits of placenta becoming lodged in a developing embryo. Other experts think proteins produced by the placenta could be linked to the development of birthmarks.

Could birthmarks be proof of reincarnation?

Another theory about birthmarks is that they are linked to past lives. According to the paper "Birthmarks and Birth Defects Corresponding to Wounds on Deceased Persons," written by researcher Dr. Ian Stevenson, roughly one-third of children claiming to remember a previous life either have birthmarks or birth defects that correlate to wounds suffered in the previous life.

While it would be easy to dismiss this as a child's imagination coming into play, here's where things get spooky: All of the children cited by Dr. Stevenson in the paper remembered living the lives of people who were actually proven to have existed and to have actually suffered these injuries. 

Stevenson concluded that this doesn't just explain what causes birthmarks, but also proves that reincarnation must be real.