In this heart-rending psalm, David begs for forgiveness for his relationship with Bath-Sheba.
While David does state that he was "begotten in sin," or in other words, that he may have been born with the character trait of intense passion, he does not cite it to free himself of guilt. In verse 5, he owns up to his transgression and does not try to absolve himself. David accepts full responsibility for his behavior, even if it comes from an inherited trait.
How refreshing is this thought! How different it is from the teachings of modern psychology, which so often scapegoat parents and excuse even the grossest misbehavior by arguing that the person was a victim of early-life experiences or influences that distorted his or her values, and hence should not be held responsible for subsequent misdeeds.
In this exquisite psalm of teshuvah (repentance), David rejects this position. He says that we must assume responsibility for our behavior, regardless of factors from our past.