Why is family history so important to the Jews?

Matthew 1:2-26 and 1 Chronicles 9:39-44

(http://bit.ly/1hso0UU and http://bit.ly/NzB0gL)

This is a questions I have always wondered (and I'm pretty sure I'm not the only one) why in several places in the scriptures there are so many verses and chapters about there ancestors. I understand a little bit about why its put in Matthew, So the Jews would know that Jesus Is the literal king of Israel descended from David, But I still had no idea why it was all over the old testament as well until recently when I learned a few things about Jewish culture.

Its only really in modern history that people have developed the mindset of life is what you make it, in many generations past who you where and what you were like was very influenced by who your family was. If you could prove you were from a certain family of people then that would immediately prestige in the community where you live. As a result many Jews would know a long way back into their family tree just from memory and any record of there family trees would be precious and very well kept. They would either be meticulously copied after several years or if you were rich enough then you would have it engraved in metal plates so that they would last a very long time. 

Partially because of this culture of being what you ancestors made you they had some great respect for their ancestors. This leads me onto a second reason why their family history was kept so carefully. Something called being baptised on behalf of the dead. I don't have the time or the space to finish this topic you guys know what to look forward to in my next blog but for those who are interested of have questions I'll give you a few scriptures to look at: 1 Peter 3:18-19, 1 Corinthians 15:29 and John 11:25