We can see a biformal bias in the essence of our Homo sapiens architecture. But that bias appears in many other known life forms too. Thus we see inherent structural preferences in the design of Earth life forms. We see significant use of biforms which affect our propensity to SOM's biformal thinking. Perhaps the largest environmental agent of our known world's biformal bias is species survival.
Survival requires simplicity, speed, and efficiency in multiple ways.
Similarly our ancestors needed security and practiced flight to escape based on very fast biformal decisions. This discussion is vastly oversimplified, but it gives a glimmer of some possible sources of our latent biformal predilections. Some derivatives of biformal thought are static thinking, centric thinking and Boolean logic. Static thinking is the stuff of extinction. Because it is easier.