My sister just had a baby girl a week ago. She was born with a light strawberry birthmark on her forehead and left eyelid. Her sister, now 6, was born with a birthmark on her forehead and right eyelid. My sister, their mother, was born with the same birthmark (in my sister’s and older niece’s cases, the faded in infancy). I just found out another relative (1st cousin once removed?) was born with a similar birthmark.
Just a remarkable coincidence, or is there a hereditary aspect of birthmarks?