With the advent of the Gaia astrometry mission and the constantly improving geodetic VLBI program providing both optical and radio reference frames with precisions better than 0.1 mas, challenging questions arise about identifying which mechanisms are behind the optical emission as well as other emissions at higher energies, especially the γ-ray emission. We use data from Gaia EDR3, the radio ICRF3, and GeV fluxes from the Fermi-LAT 4FGL catalog for a sample of about 800 common active galactic nuclei (AGN), dominated by blazars (BL Lac and FSRQs). We investigate the general trends of such populations in terms of geometry, classification, color indices, and GeV emission.