The Inner Colonies are linked to Earth almost as closely as the Core Worlds.  Most colonists came from the many aspects of life their nation enshrined.  And they are located inside The Wall of interstellar debris that separates us from the outside galaxy.  Because of that, they are firmly part of Earthspace, and share much more in common with Earth and the early colonies than those outside The Wall.  They are worlds full of blending cultural and racial lines.