My cofounder is my brother and communication is far and away one of our biggest challenges. In our case the style familiarity and family connections actually compound the delicacy of how we go about growing and changing our routines. To say I've learned more about myself since cofounding a company than in any prior endeavor would be an understatement, and I've done some pretty whacky things in the past in an effort to test my limits. (reality tv, expat, changed my name, etc) Were we both not at points in our lives where we are receptive and careful with criticism there's no way we have made it this far. One of our clutch mentors ends up being another brother who knows us both very, very well. I can't imagine how we'd get through tough times without that well known second opinion, or how impossibly impenetrable a cofounder relationship is to outsiders who haven't done it before. Hat tip to Mr. Harris for calling this out!