While distinct regional varieties descended from the older rural dialects still exist, the spoken and written language is uniform and standardized. Some dialects differ considerably from the standard language in grammar and vocabulary and are not always mutually intelligible with Standard Swedish. These dialects are confined to rural areas and are spoken primarily by small numbers of people with low social mobility. Though not facing imminent extinction, such dialects have been in decline during the past century, despite the fact that they are well researched and their use is often encouraged by local authorities. According to recent genetic analysis, both mtDNA and Y chromosome polymorphisms showed a noticeable genetic affinity between Swedes and other Germanic ethnic groups. For the global genetic make-up of the Swedish people and other peoples, see  and.  Paternally, through their Y-DNA haplogroups, the Swedes are quite diverse and show strongly of Haplogroup I1d1 at over 40% of the population tested in different studies, followed by R1a1a and R1b1a2a1a1 with over 20% each and haplogroup N1c1 with over 5% at different regional variance. The rest are within haplogroups J and E1b1b1 and other less common ones. Maternally, through their mtDNA haplogroups, the Swedes show very strongly of haplogroup H at 25–30%, followed by haplogroup U at a 10% or more, with haplogroup J and T, K at around 5% each. The largest area inhabited by Swedes, as well as the earliest known original area inhabited by their linguistic ancestors, is in the country of Sweden, situated on the eastern side of the Scandinavian Peninsula and the islands adjacent to it, situated west of the Baltic Sea in northern Europe. The Swedish-speaking people living in near-coastal areas on the north-eastern and eastern side of the Baltic Sea also have a long history of continuous settlement, which in some of these areas possibly started about a millennium ago. These people include the Swedish-speakers in mainland Finland – speaking a Swedish dialect commonly referred to as Finland Swedish (finlandssvenska which is part of the East-Swedish dialect group) and the almost exclusively Swedish-speaking population of the Åland Islands speaking in a manner closer to the adjacent dialects in Sweden than to adjacent dialects of Finland Swedish. Estonia also had an important Swedish minority which persisted for about 650 years on the coast and isles.