The fact remains if IQ is tapering off in the late 20's, the a child born to the parents in their 30's may not have as high an IQ as the parents. Personally my parents were in their mid-20's when I crawled out of the evolutionary slime, and in a sense I agree with you on the maturity and economic front - both factors were issues - and I think there has been growth there since, and my younger siblings had it better as far as maturity went, but honestly I wouldn't have it any other way, at least I know I got the best evolutionary shot I could get, lol! :-)