SIMBAD references

This paper is the last in a series investigating the optical properties of a sample of mid-IR warm Seyfert galaxies and of a control sample of mid-IR cold galaxies. In the present paper I parametrize the morphologies and interaction properties of the host galaxies and combine these with the major conclusions in my previous papers. My results confirm that nuclear activity is linked to galactic interactions. I suggest an alternative view to the simple orientation-obscuration model postulated for Seyfert types 1 and 2 that takes into account the time evolution of their environmental and morphological properties. Within this view, the distinction between warm Seyfert 1 and 2 galaxies is not one of simple orientation; the latter might instead represent an earlier evolutionary stage, with properties intermediate between the (starburst-dominated) cold galaxies and the (AGN-dominated) warm Seyfert 1 galaxies.