In the book of Genesis, there are several genealogies. At first, they appear to be a transition from one part of the story in Genesis to the next, jumping ahead many, many generations. But there are a couple of interesting features that say something about human nature as it has become, and the plan of God.
Typical treatments contrast the "ungodly line of Cain" and the "godly line of Seth." But it appears that both lines had their problems. Methuselah was still alive during the flood, but was not saved. The wickedness on the earth was great, and every thought of men was continually on evil (Gen 6:5). Only Noah found favor in the eyes of the Lord.
Chapter 5 says that God made Adam in the likeness of God, but then it says that Adam had a son, Seth, who was in the likeness of Adam, not God. In other words, Seth is one step removed from God! Sin had come into the world, and had corrupted everything (Romans 8:18-23). The effect of sin was not limited to Adam and Eve, but all who came after them. Even though the guilt of specific sins is not inherently passed on (Ezek 18:20), the power of sin has affected all who are descended from Adam (Romans 5:12-21). Paul usually refers to it as the "flesh," which is that corrupted human nature that tends to sin and is not able to subject itself to God (Romans 8:7; Galatians 5:17). That is why Paul says that in Adam, all die (1 Cor 15:22). There is a debate among theologians as to whether this corrupted nature, this power of sin that is passed on from generation to generation, is genetic or social. The nature verses nurture debate really does not help, because the result is still the same (Romans 5:19). The condition of the world during the time of Noah is an indication of the power of sin. It still gets passed down from generation to generation.
There are a couple of indications that suggest it is not impossible for one to be pleasing to God, however. Enoch walked with God and God took him (Gen 5:24). His son, Methuselah died in the flood. What God tells Cain also seems to indicate that it was not impossible. In 4:7, God tells Cain that sin is like a wild beast waiting to pounce on him, but "you must master it." Then there is Noah, the only one on the face of the earth who found favor with God. Finally, there is Jesus, who became human yet was without sin. So, this suggests that though it is not impossible to find favor with God with a nature corrupted by the sin that began with Adam, it is highly improbable. The only realistic hope is for transformation.
Through his atoning work on the cross and gift of the Spirit, Jesus reverses this trend (Romans 5:18; 1 Cor 15:45). Our Lord renews us through the power of the Spirit (Romans 8:13-15; Titus 3:5). We have a new nature and are being transformed into His image by the power of God (2 Cor 3:17-18). Only the Son can truly free us from the power of sin so that we can be Children of God. This is why Jesus says, "I am the way, and the truth, and the life; no one comes to the Father but through Me" (John 14:6).