This verse goes through the genealogy very quickly. Interestingly, while the Lamech in the line of Cain fathers a number of people who will be noted later, nobody is said to do much of anything before then. They chose to ignore God, so God, sadly, let them have free choice.
The same goes on today. People get so caught up in the world that they forget about God completely. They forget they have a Maker, a Creator, Who is looking out for them. One who loves them and longs to nurture them, if they will only come to Him. Remember, His first words to the first sinners were “Where art though” – a fact no doubt told to those of Cain’s line by those of Seth’s. However, as we’ll see at the end of chapter 4, instead of coming to Him with repentant hearts, people chose to start going away from Him far before any of the other things which will be mentioned in the interceding verses.