Perhaps because of inadvertent selective breeding the average 18 year-old will have a slightly lower IQ than the average person from an older generation.
And, by the way, this is NOT sarcasm but an observation I’ve made.
I think studies have shown a decline in human intelligence over the past few decades. Can’t find the source but I did read that.
Actually we can jump to the ending: “David Hogg.” Now we don’t have to go through the statistical proofs.