^^^ I kinda agree, since there are countries that have formally placed limits on the number of children families can have. China's population is falling off because of past limitations on family size. And now that the restrictions have been lifted, people seem to like smaller families. So, they aren't changing.
And it is similar for many countries. To replace the population in a country, parents need to have on average 2 children per family... one to replace the father, and the other to replace the mother. But many Western countries don't have this, now. It's less.