So remember, the way that we carry out these pedigrees is by beginning is by assuming something. And then with that assumption, we have to check the consistency of that particular pedigree. That is, is this consistent with the information that is given to us in this pedigree? So what do we mean by autosomal recessive? So let's suppose the gene we're talking about is color blindness. And let's designate color blindness with the gene given by letter B.