Actually, the reason the drinking age is not 18 is because the Reagan administration, supported by a bipartisan congress, passed the unconstitutional National Minimum Drinking Age Act of 1984 in an effort to micromanage state political affairs. This law didn't set the minimum age, because that is not permitted under the Constitution. Rather it makes an end-run around the document each and every one of them swore to support and defend to change
Title 23 of the US Code to require the states to change their own drinking age laws or risk losing 10% of their allotted federal highway funds ... funds required by the Constitution, btw.
I would love to know how Gingrich and Paul voted on that, since they were both in office at that time.