Who do you think?
If you CHOOSE a course of action that leads to negative results, who is to blame? If you cheat on your spouse, get busted, have to go to court, lose custody of your children etc etc...whos fault is that? YOURS!
Many things happen because of what people CHOOSE.
Some "negative" or "bad" things that happen are nothing more then the result of sin. Sin causes death and destruction...of human beings, environments, etc etc.
Most things that are considered "acts of god" are not...they are results of sin.