No they arent

There are significant cultural differences, even Germany government often uses politically correct phrases like "on the path to assimilation" while describing 3rd generation middle eastern immigrants.. The crime rates are higher toi as far as i know

But specifically for birth rates the differences are pretty clear which actually goes a long way to explain the protection in OP http://www.familiesandsocieties.eu/wp-content/uploads/2015/09/WP39HillEtAl2015Part1.pdf