General Social Survey participants were asked, "What do you think is the ideal number of children for a family to have?" I focused on people from the last two decades of surveys (2000-2018) who were childbearing age (18-45). Immigrants and a small percentage of respondents who answered, "as many as people want," were excluded (sample size = 3,390):
Mean ideal family size
The top graph shows results for men and women, and the bottom one is for blacks and whites (other non-whites were omitted).
Ideal family size drops a lot as IQ increases, and the pattern is similar for males and females. People with IQs in the low 60s think more than three children is the right size, while the smartest group say the ideal size is a little over two.
Looking at the bottom graph, the drop for blacks is even sharper than for whites.
To the extent that people have the number of children they think is ideal, American attitudes are dysgenic. The wrong people are idealizing large families. With each generation, we're getting genetically dumber.