Ryukyu Shimpo (9/17/14) reported that “Modern people living in the Ryukyu Islands are genetically more closely related to those in the main islands of Japan than people in Taiwan or mainland China, a research team has found.” The following are excerpts from the article:
– Previous research results have also shown the people of the Ryukyu Islands are more similar to those in the main islands of Japan than mainland China or Taiwan from bones and DNA analysis of remains.
– The team collected DNA from a few hundred of people from the main islands of Okinawa, Miyako and Yaeyama islands…. The results showed the native people of the Ryukyu islands and those of Taiwan are in different genetic groups.
– The researchers said further investigation was needed.
See the original article, “Genetic DNA of Okinawan people similar to people in the main islands of Japan.”
liuchiuan 
Interesting article. Okinawans and mainland Japanese are similar, but not the same.
I suspect the genetic link between the Okinawans and the mainland Japanese lies in the fact that we derive from the Jomon people, an ethnic group thought to be related to the Ainu.
People in mainland Japan apparently are more so a mixture of Jomon and Yayoi, an ethnic group that migrated to the Japanese islands from Korea in ancient times, while the Okinawans on the other hand are more so purer Jomon.
I believe the Okinawans mixed with the people of mainland China to a certain extant. I’m also starting to believe the mainland Japanese are more Jomon in their ethnic lineage than what was originally thought.