I should have specified 2x real income e.g. income indexed for inflation. If your parents started working in '78 they have likely had a nearly miraculous wealt

I should have specified 2x real income e.g. income indexed for inflation. If your parents started working in '78 they have likely had a nearly miraculous wealth transfer from owning a home in a world with declining real interest rates. As you noted, their income rose 650% due to inflation - and their housing cost was likely fixed.