IQ started falling in Europe before the US. It seems the US has finally caught up. It doesn't seem to be due to immigration, as countries that have less immigration have sometimes had more average IQ drop. It also doesn't seem to be due to dysgenic mating (eg, Idiocracy), as we can see IQ drops within the same family (younger siblings vs. older siblings).
I wonder if it's due to the changing nature of kids' free time. When I was growing up, we played with actual toys, blocks, Legoes, board games, that sort of thing. We also had actual physical books to read. Now days, kids are spending time in front of cell phones or tablets, and probably spend alot less time reading.
