I don't know whether we do increase in intelligence anymore there are problems that increase in the most intelligent populations that might put a limit on it. As to whether some part of intelligence can be accounted for with epigenetics I'd bet on it as it's a complex trait but you'd have to ask a researcher.

At least for now, we can still optimize information density and distribution. We stand on the shoulders of giants, but we need a way to get more people onto their shoulders so that someone else might stand on ours.