In American crime movies, policemen search crime scenes for anything that might belong to a criminal-- bits of fingernail , blood or hair-- in order to find out who they are. What they hope to find is the key to their identity--their DNA. DNA is the chemical that contains a person's genetic makeup. Every person, except for identical twins, has unique DNA information. That is why we can use it to identify someone. There is no doubt that DNA evidence is becoming a very powerful tool for law enforcement  officers. In the US, all 50 states and the federal government keep DNA databases of some criminals after they have been convicted . Whenever a crime happens, the police collect DNA from the crime scene and compare this with samples they already have in the criminal database. If they match any suspect in the database, then they've caught their criminal. Even if they don't, the DNA sample can still be used to determine the person's sex, height, hair and eye color1 and other characteristics. This helps police to create a physical profile of the criminal. Some people feel that the database should be made bigger to contain everyone's DNA and help to solve many more crimes. This would also avoid mistakes when someone is wrongly convicted of a crime. DNA doesn't make mistakes. However, other people are worried that it would violate their privacy. Someone's DNA can be used to gather information such as the person's family and ethnic  background, whether he or she has a gene mutation or certain genetic diseases, and other personal issues. People are afraid that this information might be used inappropriately. They may fear that employers might read it and treat them differently. People may also be afraid that personal data might get into the hands of insurance firms or loan companies. For example, if they knew from your DNA that you had a genetic risk of a serious disease, they might be able to refuse you life insurance, a loan, or even a job.  Clearly, the use of DNA evidence will continue to help the police solve crimes. However, social and ethical concerns about DNA will also remain a topic of debate. Some people suggest building a database containing everyone's DNA because   _  .
it would mean fewer people commit crimes. it would make it more convenient for the government to gather information it would help the police identify suspects more efficiently and accurately such a database could be helpful in many more fields besides solving crimes