my new sentence-making!~~~help me to revise them~I love all of you dears~~~

Back: 1, Your father is standing behind you. or your father is standing on your back side. 
2, He went back home to get the keys.
3, <font color="#ff0000">I am feeling backache.
4.My family backs my decisions always
</font>.
5,(Here I need to make a sentence with “back” when it means “support” or “approve”, please help me to make this sentence, thanks!)

Balance: The development should keep a balance between both natural environment and economic environment.

Base: This theory was based on the result of the experiment.

Behavior: A person’s behavior reflects his or her cultural background. (Here I want to express the meaning “breeding”, I am not sure culture or breeding, which could be more suitable?)

Belief: He kept his beliefs at the bottom of his heart <font color="#ff0000">and</font> never changed his beliefs.