Witch Marks

Oil painting of a woman being examined for a witch mark. Her dress has been pulled down to her waist, exposing her back to which someone is pointing. A man sits at a desk with quill and paper, while examining the woman's back.

The ancient Greeks marked the flesh of those considered to be morally deficient and these marks were called 'stigma'. But with the growth of Christianity in Europe, natural marks on the body came to be seen as 'stigma', too. 

For example, during the witch hunts in the sixteenth century, witches were believed to carry a visible mark on their bodies that would confirm their witch status. To have a 'witch's teat' was used as proof that the devil visited the woman in the night to suckle and was seen as a form of maternal perversion.

In Malevolent Nurture: Witch-hunting and maternal Power in Early Modern England, Deborah Willis writes:

'Witches were—or were believed to be-mothers "gone bad," women past childbearing years who used their mothering powers against neighbors who had enraged them. To acquire their magic, women fed and cared for demonic imps as if they were children. In exchange, imps would bring sickness and death to other households-often the households of younger mothers.' ​

Sources:
'Examination of a Witch' by Tompkins Harrison Matteson (1853).
An Ancient Stigma, Ancient World Magazine. 
'Stigma and Social Identity' in Deviance and Liberty by Irving Goffman.
Malevolent Nurture: Witch-hunting and maternal Power in Early Modern England by Deborah Willis.