DNA studies in recent decades conclusively revealed that there is virtually no Hebrew DNA among Native Americans.
There is DNA evidence that the native American’s did not have the origins that the Book of Mormon purports that they do. The DNA evidence suggests that the Native Americans origins were not from the middle east at all, as the Mormon church has claimed for years, and instead that they were from Asia.
http://en.wikipedia.org/wiki/Genetics_and_the_Book_of_Mormon
Before DNA evidence was found the Mormon Church even produced a filmstrip, which was shown by their missionaries in many countries, called Ancient America Speaks, where it presented what the rest of the world identifies as Inca and Mayan ruins, as ruins of the Book of Mormon peoples.
It’s also interesting to note that almost without exception, in the past 75 years or so, every Mormon temple that has been dedicated in Central and South America, and the Islands of the Pacific, has, in its dedicatory prayer, been mentioned as a place that will bring the blessings of the Gospel to the Lamanites who presumably make of the principal population of that country.
Now that DNA evidence has come out, the Mormon church has been trying to cast doubt on the DNA evidence, including an article on their official site, where they try to discredit the science and label it as inconclusive. As much as they want to accredit genetic drift to the reason why there is no hebrew DNA in Native Americans, given all of the accounts in the Book of Mormon, there were no other people in the land to whos DNA they could mix with that would override the Hebrew DNA. Even if there were, it’s highly improbable that their DNA would be able to override ALL of the different Native American tribes across the Americas.