biological mother vs mommy

biological mother

noun
  • The woman from whom one inherits half of one's DNA and who is the source of one's mitochondrial DNA. 

mommy

verb
  • To treat someone like a mother would; to mother someone. 

noun
  • Mother. 

adj
  • Characteristic of a mother; motherly. 

How often have the words biological mother and mommy occurred in a corpus of books? (source: Google Ngram Viewer )