Where did DNA instructions come from?

You're asking if DNA is accurate and who said so???

If the courts of the land order a DNA test to establish paternity that test is considered to be 99.9 percent accurate.

"What are the odds that two random people will have those same markers in common? Unfortunately, it is POSSIBLE that two unrelated people will have the exact same markers—just due to a chance occurrence. But, this type of chance occurrence is extremely rare. It is like the odds of flipping a coin and having it turn out to be heads a thousand times in a row—it is very unlikely to happen, but it COULD happen.

Because paternity testing involves an element of probability, it is not possible to conclude with 100% certainty that someone is the genetic father of a child (see paternity testing). Just as it is not possible to say that someone will not flip heads a thousand times in a row. It is possible for nonrelated individuals to share very similar markers (again this is extremely unlikely, but possible).

Accordingly, to prove paternity the bar is not set at 100%, because it is not possible to achieve that degree of certainty. You can never completely rule out the possibility that a non-related individual might share the same genetic markers. As such, the standard for paternity is never 100%, but it is set as high as possible (usually at least at 99%) in order to achieve a high degree of certainty."

That is a real problem. It gets into religion real fast. Scientists consistently speak as if there were some intelligent design in natural things, but they panic if you call it "intelligent design". Instructions come from an instructor, but scientists reject the concept of a being superior to themselves.