They’re after blood. A new University of Pennsylvania study found that gun violence in movies rated PG-13 has become more acceptable to viewers with children under 17. Parents appear especially desensitized to violence they see as justified and when the consequences are omitted. However, they largely recommended such content for kids over 15, leading some to suggest a new PG-15 rating. Study author Daniel Romer said deleting blood and suffering from violent scenes allows studios to avoid R ratings but could still potentially harm young moviegoers.