Rather fascinating that Yemen has gotten more religious over time. Perhaps the result of sectarian actors playing groups off of each other? Would have loved to have data for Syria on these questions.
I don’t know for sure why Yemen has gotten more religious, but the fact that part of Yemen was Marxist until the early 1990s could be a reason. No more Marxism, more religion.
That's possible, but the time period polled is far more recent. Perhaps you're right, and kids are being raised more religious than their forebearers who grew up in the People's Democratic Republic of Yemen.