Even science doesn't know it all. Knowledge increases, even when there are established "facts". <- science is a tool that allows us to know more about our universe, but unfortunately our knowledge is restricted to the technology and knowledge we can use.
and more than half of the ones that are 'blood' sure as hell aren't my family. not loyal, not loving. and definitely not caring, so they are not my family. i have more friends that are closer to being my family than my relatives are.