In this day & age, blood does not make you family! The people that share your blood, are usually the ones to hurt you the most! I have my family that are full with the people that I became friends first!
If you don't treat someone right odds are their attitude towards you will change. Do your best to avoid this. And if you find someone needs an attitude adjustment then really ask yourself why and what contributed to it.
I live my life by this I completely cut people out if they hurt me enough. Some people judge me harshly because they think that I'm to harsh. But the truth is I cut people out because I find that this is the only way to continue with my life.