to cause to hold or exhibit a particular bias; to influence, especially unfairly: a tearful plea designed to bias the jury; a survey biased toward highly educated people. 11.
Moles are caused when cells in the skin, called melanocytes, grow in clusters or clumps. Melanocytes are distributed throughout your skin and produce melanin, the natural pigment that gives your skin its color.
In addition to causing mutations in living organisms, as for example when exposure to a mutagen leads to the development of a cancerous tumor, mutagens can also cause birth defects.