Common concerns about genealogical DNA testing are cost and privacy issues. Some testing companies retain samples and results for their own use without a privacy agreement with subjects.Autosomal DNA tests can identify relationships with good accuracy out to about 2nd cousin, but they have limitations. In particular, transplants of stem cell or bone marrow will produce matches with the donor. In addition, identical twins (who have identical DNA) will share higher amounts of DNA with a greater range of relatives.Testing of the Y-DNA lineage from father to son may reveal complications, due to unusual mutations, secret adoptions, and false paternity (i.e., that the perceived father in a generation is not the father indicated by written birth records). According to the Ancestry and Ancestry Testing Task Force of the American Society of Human Genetics, autosomal tests cannot detect "large portions" of DNA from distant ancestors because it has not been inherited.With the increasing popularity of the use of DNA tests for ethnicity tests, uncertainties and errors in ethnicity estimates are a drawback for Genetic genealogy. While ethnicity estimates at the continental level should be accurate (with the possible exception of East Asia and the Americas), sub-continental estimates, especially in Europe, are often inaccurate. Customers may be misinformed about the uncertainties and errors of the estimates.Some have recommended government or other regulation of ancestry testing to ensure its performance to an agreed standard.A number of law enforcement agencies attempted to coercegenetic genealogy companies that store customer's data into giving up information on their customers who could match cold case crime victims or perpetrators. A number of companies fought the requests.
For people with European maternal ancestry, mtDNA tests are offered to determine which of eight European maternal "clans" the direct-line maternal ancestor belonged to. This mtDNA haplotype test was popularized in the book The Seven Daughters of Eve.
The pre-columbian indigenous people of the United States are called "Native Americans" in American English. Autosomal testing, Y-DNA, and mtDNA testing can be conducted to determine the ancestry of Native Americans. A mitochondrial Haplogroup determination test based on mutations in Hypervariable Region 1 and 2 may establish whether a person's direct female line belongs to one of the canonical Native American Haplogroups, A, B, C, D or X. The vast majority of Native American individuals belong to one of the five identified mtDNA Haplogroups. Thus, being in one of those groups provides evidence of potential Native American descent. However, DNA ethnicity results cannot be used as a substitute for legal documentation. Native American tribes have their own requirements for membership, often based on at least one of a person's ancestors having been included on tribal-specific Native American censuses (or final rolls) prepared during treaty-making, relocation to reservations or apportionment of land in the late 19th century and early 20th century. One example is the Dawes Rolls.
Melungeons are one of numerous multiracial groups in the United States with origins wrapped in myth. The historical research of Paul Heinegg has documented that many of the Melungeon groups in the Upper South were descended from mixed-race people who were free in colonial Virginia and the result of unions between the Europeans and Africans. They moved to the frontiers of Virginia, North Carolina, Kentucky and Tennessee to gain some freedom from the racial barriers of the plantation areas. Several efforts, including a number of ongoing studies, have examined the genetic makeup of families historically identified as Melungeon. Most results point primarily to a mixture of European and African, which is supported by historical documentation. Some may have Native American heritage as well. Though some companies provide additional Melungeon research materials with Y-DNA and mtDNA tests, any test will allow comparisons with the results of current and past Melungeon DNA studies
Y-DNA and mtDNA testing may be able to determine with which peoples in present-day Africa a person shares a direct line of part of his or her ancestry, but patterns of historic migration and historical events cloud the tracing of ancestral groups. Due to joint long histories in the US, approximately 30% of African American males have a European Y-Chromosome haplogroup Approximately 58% of African Americans have at least the equivalent of one great-grandparent (13%) of European ancestry. Only about 5% have the equivalent of one great-grandparent of Native American ancestry. By the early 19th century, substantial families of Free Persons of Color had been established in the Chesapeake Bay area who were descended from free people during the colonial period; most of those have been documented as descended from white men and African women (servant, slave or free). Over time various groups married more within mixed-race, black or white communities.According to authorities like Salas, nearly three-quarters of the ancestors of African Americans taken in slavery came from regions of West Africa. The African-American movement to discover and identify with ancestral tribes has burgeoned since DNA testing became available. African Americans usually cannot easily trace their ancestry during the years of slavery through surname research, census and property records, and other traditional means. Genealogical DNA testing may provide a tie to regional African heritage.
As discussed above, autosomal tests usually report the ethnic proportions of the individual. These attempt to measure an individual's mixed geographic heritage by identifying particular markers, called ancestry informative markers or AIM, that are associated with populations of specific geographical areas. Geneticist Adam Rutherford has written that these tests "don’t necessarily show your geographical origins in the past. They show with whom you have common ancestry today."The haplogroups determined by Y-DNA and mtDNA tests are often unevenly geographically distributed. Many direct-to-consumer DNA tests described this association to infer the test-taker's ancestral homeland. Most tests describe haplogroups according to their most frequently associated continent (e.g., a "European haplogroup"). When Leslie Emery and collaborators performed a trial of mtDNA haplogroups as a predictor of continental origin on individuals in the Human Genetic Diversity Panel (HGDP) and 1000 Genomes (1KGP) datasets, they found that only 14 of 23 haplogroups had a success rate above 50% among the HGDP samples, as did "about half" of the haplogroups in the 1KGP. The authors concluded that, for most people, "mtDNA-haplogroup membership provides limited information about either continental ancestry or continental region of origin."
2016年5月29日（日曜日）雨のため、セーフティカー先導によるスタートとなった。セーフティカーは7周目に去り、ポールポジションのダニエル・リカルドは2位ニコ・ロズベルグがブレーキの温度管理に苦しみペースが上がらなかったこともあり差を広げていく。メルセデスは16周目にルイス・ハミルトンを前に出すようにロズベルグへ指示し、ハミルトンが2位に浮上した。路面が乾き始めた23周目にリカルドはタイヤをインターミディエイトに交換、これでハミルトンがトップに立った。ハミルトンは31周目にウエットからインターミディエイトを挟まずウルトラソフトに交換、翌周にはリカルドもスーパーソフトに交換したが、レッドブルのピットクルーがソフトタイヤと勘違いしたためタイヤ交換に時間を要することになった。リカルドはハミルトンの後ろでコースに復帰し、以後はリカルドがハミルトンを追走する状況のままフィニッシュ、ハミルトンが今シーズン初勝利を挙げた。ハミルトンにとって8年ぶりのモナコGP優勝であり、メルセデス移籍後は初めてとなる。メルセデスはF1通算50勝目。ロズベルグは最後までペースが上がらないまま7位で終わり、アイルトン・セナ以来となるモナコGP4連覇を逃した。セルジオ・ペレスはタイヤ交換の戦略が功を奏し3位表彰台を獲得した。マクラーレンはフェルナンド・アロンソが5位（ホンダ復帰後最高位タイ）、ジェンソン・バトンが9位に入り今シーズン2度目のダブル入賞。ピットミスで優勝を逃したリカルドに笑顔は一切なかった。前年もトップを走っていたハミルトンが誤ったタイミングでピットに呼び出されたことで優勝を逃しており、この年もピットによって明暗を分ける結果となった。