In 2002 a 52-year-old woman needed a kidney transplant. She and her family underwent genetic testing to see if one of her children could serve as a kidney donor (healthy adults can donate one kidney with few side effects). Genetic tests suggested that this woman was not the biological mother  of her children. Her husband was genetically identified as the biological father, she had clearly given birth to the children, and the couple has not had medical interventions to get pregnant. So how could someone give birth to children who did not seem to be biologically hers? Clearly this story is unusual, but it brings to mind a number of questions about how babies are usually made, and how our understanding of the typical biological process of baby-making could help us understand this scientific puzzle.
- Note about the term “mother”: Not all females who have babies identify with the gendered term mother. For clarity and brevity, this term is used in this chapter in reference to females who are producing offspring. We will also use the term "egg-parent" to be more biologically accurate and inclusive. ↵