  It is shown that several habitability conditions (in fact, at least seven
such conditions) appear to be fulfilled automatically by circumbinary planets
of main-sequence stars (CBP-MS), whereas on Earth these conditions are
fulfilled only by chance. Therefore, it looks natural that most of the
production of replicating biopolymers in the Galaxy is concentrated on
particular classes of CBP-MS, and life on Earth is an outlier, in this sense.
In this scenario, Lathe's mechanism for the tidal "chain reaction" abiogenesis
on Earth is favored as generic for CBP-MS, due to photo-tidal synchronization
inherent to them. Problems with this scenario are discussed in detail.
