Large Families:

via Robin Hanson:

"..the 5% of women in the United States who … have five or more children on purpose … These women are a different kind of religious, full of such faith that they seem to be living and working on a separate planet of possibility. How their stories tend to unfold: They decide they want kids. They have some, then they have more and more. They find a kind of deep satisfaction in it, especially after the fourth or fifth one, … interviewees speak in almost mystical ways about the experience."