The two notable exceptions to this structure are Pinghua and Tanka people, who on their patrilines, bear a closer genetic resemblance to aboriginal peoples, but have Han matrilines. The Tanka are a group of boat-dwellers who speak a Sinitic language and who claim Han ancestry, but who have traditionally faced severe discrimination from the other southern Han subgroups. Unlike the Guangdong, Fujian and Hainan Han (whose dominant Y-chromosome haplotype is the Han patriline O2-M122), the Tanka have been shown instead to have a predominantly non-Han patriline similar to Daic peoples from Guizhou. However, matrilineally, the Tanka are closely clustered with the Hakka Han and Teochew Han, rather than with Austronesian or Austroasiatic populations, thus supporting an admixture hypothesis and validating, even if only partially, their own claims to Han ancestry.thumb|310x310px|A PCA graph illustrates the genetic differences among Han Chinese subgroups.
The two notable exceptions to this structure are Pinghua and Tanka people who on their patrilines bear a closer genetic resemblance to aboriginal peoples but have Han matrilines The Tanka are a group of boat-dwellers who speak a Sinitic language and who claim Han ancestry but who have traditionally faced severe discrimination from the other southern Han subgroups Unlike the Guangdong Fujian and Hainan Han (whose dominant Y-chromosome haplotype is the Han patriline O2-M122) the Tanka have been shown instead to have a predominantly non-Han patriline similar to Daic peoples from Guizhou However matrilineally the Tanka are closely clustered with the Hakka Han and Teochew Han rather than with Austronesian or Austroasiatic populations thus supporting an admixture hypothesis and validating even if only partially their own claims to Han ancestrythumb|310x310px|A PCA graph illustrates the genetic differences among Han Chinese subgroups