One of the new features in WordPress 4.3 is a Site Icon (also known as favicon). It allows you to specify what icon should be associated with your website. This displays in browser tabs and mobile bookmarks.
Just go to Appearance > Customize > Site Identify and you’ll find a Site Icon uploader in the left panel. If you upload an image, WordPress will automatically resize it to the proper sizes and insert the code into your page for browsers to see it.
Genesis has a similar feature built-in (although there’s no UI for it). In Genesis, if you have a favicon.ico (or .gif, .png, .jpg) in your theme’s /images directory, Genesis will use that as your favicon and add code to the page for browsers to see it. If you don’t specify one in your theme, the icon defaults to the favicon found in Genesis, which is why you see so many Genesis websites with the “G” as their favicon.
Genesis 2.2 and later will have this feature disabled already, but if you want to use WordPress’ Site Icon with Genesis 2.1 you should disable the Genesis feature so you don’t end up with two icons in your site’s code. Simply add this to your child theme’s functions.php file:
|* Disable the Genesis Favicon|
|* @author Bill Erickson|
|* @link http://www.billerickson.net/wordpress-site-icon-with-genesis|
|remove_action( 'wp_head', 'genesis_load_favicon' );|