Death Penalty

• is moral because my family welcomed the revenge and closure after the murder of my brother

This argument in my opinion is justifiable because it has a more personal approach. Criminals in our society always have a punishment, and when they take somebody elses life, the punishment is stronger or worse. Perhaps a harsh punishment such as a death penalty can help reduce the murder rate as it creates fear.
If the murder had no reason at all, then the desire for revenge is stronger, as it was something unfair to do. Maybe it did have a reason, maybe the person that was murdered had hurt the other person or something. Im not saying that the murder is entirely justified, because i dont think someone has the right to take somebody else's life for whatever reason. Maybe the family will feel relieved knowing that the criminal's life was ended too.

Source of morality

I think that the source of morality is social because society has created moral values over time for us to follow. Our families teach us these values and we decide wether to follow them or not. For example, my parents have always told me to stay away from certain things, to not do them because they are wrong. Morality is also political, where "leaders" communicate to us what is right or wrong, and expect us to follow their moral values, for example Hitler in WW2. The same happens with religion, where leaders also communicate and tell people to do or not do certain things, for example the Catholic church with abortion or homosexual relationships.  

:)