There are 300,000,000 people in the US and the odds are great that someone has DNA or fingerprints so similar to mine that nobody can tell them apart.

There are plenty of people, many of them in the employ of the government, who feel that it's acceptable to imprison a fair number of innocent people to insure that the maximum number of guilty people receive punishment. I feel the opposite, that it's preferable to let a few guilty people go free to minimize the chances of innocents being punished. I'm not willing to submit my biological data to some database that increases the chances I may become some prosecutor's "collateral damage".