The question more should be: who monitors the child, the media or the parents? Lyrics from all types of music, as well as scenes from movies and video games can be considered more "mature," but it all depends on how the child consumes it. There are some moments where the child grows up with objectionable material but still mature into normal, functioning adults. Other times, the opposite happens. As long as you monitor the material being consumed, and how the child acts after consuming the material, it should be fine as long as you talk to the child about what's being said in the songs. If you let the media babysit your child, and the child grows up to being a murderous psychopathic lunatic, often times the blame will go to that particular media outlet. That's not where the problem lies. Ultimately, we should stop blaming the material and examine the real problem: bad parenting.