Question: why and how do we get our birth marks?

Pete Etchells answered on 26 Apr 2012:

Hi galkeviciute! Birth marks can be caused in a number of different ways – generally, they might be either an overgrowth of blood vessels, or due to too much skin pigment (called melanin) collecting in the same place. We don’t really know why people get birthmarks though! Some scientists think that it’s because when you’re developing as a baby, some cells (for some reason) don’t spread out in the way that they should, and instead group together to form a birth mark.

Hope that answers your question!