Genesis has long used an older version of the Twitter Bootstrap grid. That version is now seriously outdated. The latest version also brings responsive column classes to the fore.
I created the Genesis Bootstrap Grid plugin to enable me to use the latest version of the Bootstrap Grid without necessarily overloading my sites with all the other features that Bootstrap brings with it.
NOTE: Do not install this plugin on sites that are not running the Genesis Framework. It may break your site.
Please note, this plugin only adds the classes required to load and execute the Bootstrap Grid. It does not contain any other Bootstrap CSS.