A bit off-topic, but can a Mormon explain the reason why Mormons have a lot of kids? The simple answer would be religion, but even mainstream American Christians don't have kids at that level. I know a Mormon tech tycoon with 10 kids and another tycoon with 14 kids, lol
One is Utah was a rural state until fairly recently, so big families and farming kind of go together.
Another is a bit more 'soft' doctrinal. The general teaching in the 60s/70s as other groups were losing their big families, the LDS/Mormon idea of the pre-existence of human spirits and the importance of the instruction to Adam and Eve to:
"Be fruitful, and multiply, and replenish the earth, and subdue it"
was taken as a literal instruction for members, with general counsel to avoid birth control and a prohibition on abortion.
My parents never tried anything beyond the rhythm method to control their family size.
Current generations still refrain from abortion (generally) but otherwise aren't too concerned about using artificial methods in limiting the size of their families, especially as the expense of big families has multiplied.
Still bigger than average, but the gap is much smaller, and shrinking.