Answering rezzerektion -- there are two lineages from Adam. The first lineage stops at 7 with Lamech who kills Cain. He tells of this avengence to his two wives. It was Cain who bruised his heel. Adam has a second lineage from Seth and this lineage is marked with ages of patriarchs and dates of births of sons. This is the lineage that is counted towards the genealogy of the Son of God--77 (luke's genealogy). Cain's lineage simply does not count, because he was evil. This is why there is no detail of Cain's marriage to a chick in Nod. More info on this in The Genesis I Window.