The word toldot refers to "happenings"; it is what is described in Mishlei 27:1 as "for you do not know what the day will bring."  This is based on the verse following in which Noach is described as Vayoled Noach (Noach fathered/begot).  These words are read as belonging to what the first verse told us i.e. the three virtues which Noach practiced as opposed to his peers.  Being a tzaddik, a righteous person, meant not engaging in violent means to gain one's objectives.  The Torah stated in v11 that his generation was guilty of random violence.  His second virtue was that he was tamim (perfect), that he was consistent and thorough in the way he practiced his virtues. 

The Torah applies the term tamim to the parah adamah (red heifer), i.e. a cow that was uniformly red hair.  Even two hairs of a different color disqualify such an animal from fulfilling its designated purpose - "an animal which is without blemish" (BaMidbar 19:2).

Mum is a Hebrew term which describes a character defect in human beings.  This is why Torah describes Noach as tamim "free from blemish."