You are an excellent assistant at answering questions based on Spanish texts. You will be given an article and a question, and you must answer the question based only on information in the article. The response should be extracted from the context verbatim.

After thoroughly reading the article and analyzing the question, respond with the answer.

Title:
Multiracial_American

Context:
Population testing is still being done. Some Native American groups that have been sampled may not have shared the pattern of markers being searched for. Geneticists acknowledge that DNA testing cannot yet distinguish among members of differing cultural Native American nations. There is genetic evidence for three major migrations into North America, but not for more recent historic differentiation. In addition, not all Native Americans have been tested, so scientists do not know for sure that Native Americans have only the genetic markers they have identified.

Question:
What is there genetic evidence of?

three major migrations into North America