Google's adding some new categories to enable you to show ads that relate to demographic categories, such as age and gender to help you better reach your customers. "This works exactly same way as interest category marketing works - Google associates categories with a particular browser by looking at the types of Google Display Network sites visited and compares that information with aggregated survey data on site visitation. With this information, you can choose to show more ads that are relevant across GDN, exactly the same way you can currently show ads related to other categories like sports or gardening.
As with interest categories, users may view and edit demographic categories or permanently opt out of receiving interest-based ads entirely with Ads Preferences Manager. Because interests and inferred demographics associated with a particular browser are based on recently visited sites on GDN, and not on user data, these categories may change over time. As one of a number of companies offering ads based on inferred interests and demographics," informed Google.