Jessica, using subscribers from a single magazine to define “Makers” is always going to skew your definition.
Just thinking back to the New York Faire at the end of September, I wonder how many of the people showcasing there were subscribers. For example many of the younger people wouldn’t be as a subscription implies a regular income. Also many of the “Makes” I saw had no electronics or were made from scrap materials. Again these people are unlikely to be subscribers to a magazine specialising in electronics and kits.
I’m not denying that there is a bias towards middle aged blokes but legitimately interested to know if it is as skewed as your numbers suggest. Perhaps look at the Maker Faire website and look at the people exhibiting?