Inside STAT: Armadillo quads offer an answer to why identical twins differ 

A SET OF "IDENTICAL" ARMADILLO QUADRUPLETS. (COURTESY FRANK KNIGHT)

Lab mice are often bred to be genetically identical, but another placental mammal — the nine-banded armadillo — might have even more to offer science: They are always born as genetically identical quadruplets, saving scientists the trouble of having to create uniformity. And with identical genomes, scientists can then probe what other factors — environmental, experiential, or something else — may be driving differences among the animals, with lessons for what makes humans different. Scientists working with armadillos at the Hansen's disease (formerly known as leprosy) center in Louisiana have found, for instance, that up to 10% of the variability among quadruplets is due to randomness, a fact that could help explain how even similar genetic traits, environmental exposures, and life experiences could still add up to create wholly different people. STAT's Sharon Begley has more here.