I love telling people to read their Bible because the stories in it are sometimes astonishing. Certainly the one from today's reading of the defilement of Dinah and the retribution of her brothers falls into the category. Even the account of Jacob sets an example that is less than admirable as he lied to his brother yet again when he had the opportunity to mend the relationship.
We have to recognize a few things here. First, the culture of this time period had a very cheap view of life. Spilling someone's blood was a common occurrence, and people did not wince at it the way we do today. That is not to say that God didn't value life in the days of Genesis. The truth is that He valued it so much that He tried to start over with the flood and then again with Abraham's family. What's important to see is just how depraved things had become.
The second thing to notice is that we don't have any good examples of family. Every example of family (maybe with the exception of Job) is broken and twisted. In light of that, we have to be careful in the church that we don't pretend we have perfection when, in fact, we don't. That is not to say we shouldn't strive to live in ways that are godly. If families were perfect (or could be perfect), then Jesus wouldn't have had to die. Again, this story points us to how utterly hopeless we are without the forgiveness of Christ.