Teacher:This task is about writing a correct answer for the reading comprehension task. Based on the information provided in a given passage, you should identify the shortest continuous text span from the passage that serves as an answer to the given question. Avoid answers that are incorrect or provides incomplete justification for the question.
Teacher: Now, understand the problem? Solve this instance: Passage: Genetic history of indigenous peoples of the Americas primarily focus on Human Y-chromosome DNA haplogroups and Human mitochondrial DNA haplogroups. "Y-DNA" is passed solely along the patrilineal line, from father to son, while "mtDNA" is passed down the matrilineal line, from mother to offspring of both sexes. Neither recombines, and thus Y-DNA and mtDNA change only by chance mutation at each generation with no intermixture between parents' genetic material. Autosomal "atDNA" markers are also used, but differ from mtDNA or Y-DNA in that they overlap significantly. AtDNA is generally used to measure the average continent-of-ancestry genetic admixture in the entire human genome and related isolated populations. Question: What is the only way that Y-DNA and mtDNA change?
Student:
chance mutation