Violence Vedeo Game

What do you guys think, does video game violence actually affect children?

I researched on the internet about this the other class and a recent study conducted by Iowa State University psychologists says yes. Their study shows that “brief exposure to violent video games can cause a reduction in normal physiological reactivity to images of real violence.” This process is the same desensitization process that is used to help people get over fears of spiders or flying. All so I heard that "Basically, we introduce young children to very playful, fun, cartoonish forms of violence, with little or no blood, no real consequences to the victim or friends and family of the victim." As children grow "more realistic and more threatening elements" are added. Eventually we have adults "accustomed to and comfortable with seeing lots of blood and gore, with an exaggerated view of how much violence exists or is "normal" in modern society, and with belief systems that are supportive of use of aggression or violence."
Why we knew those fact but we still use it??