The Font property is an ambient property. An ambient property is a control property that, if not set, is retrieved from the parent control. For example, a System.Windows.Forms.Button will have the same System.Windows.Forms.Control.BackColor as its parent System.Windows.Forms.Form by default.
Because the Font is immutable (meaning that you cannot adjust any of its properties), you can only assign the Font property a new Font. However, you can base the new font on the existing font.