They have particularly harsh effect on the behaviour and usually on certain attributes like aggression. There have been many researches on this issue which all point to the same result. People, especially adolescents listening to rock culture are likely to be more aggressive and quick-tempered. They may also have an ego problem. Bad egos will always a negative effect on a child's behaviour and personality.
This has more or less an invariable outcome on studies, mood and social life. Their concentration in school depletes. Experts say, "Children who are exposed to such kind of music and lyrics at a young age tend to degrade in their studies and as a result may go into depression." They usually get angry faster and create big quarrels over small topics. They are said to become more 'rebellious' and are often prone to mood swings.
Moreover, the lyrics of the music have become more vulgar and obscene in the past decade. Parents are becoming concerned about what the child listens to and they cannot find it out due to the more frequent usage of headphones. They learn more offensive vocabulary which is not meant for their age. In some of the more severe cases a child may become addictive to rock and may find it hard to even stop listening to it. In some rare cases it has also lead to death.
Some people, the young generation in particular believe that music cannot possibly have an effect on a person's mental, physical and psychological behaviour. They also consider it affects a person positively and enhances concentration and is a means of becoming stress free.
However, this statement is not true and I believe that rock music is no less than a drug. I advise to all parents to inhibit this addiction and nip it in the bud. It is for a child's own safety that he must not listen to such music.