The first actual laws against first-degree marriage appeared during the Civil War, when Kansas banned the practice in 1858, followed by Nevada, North Dakota, South Dakota, Washington, New Hampshire, Ohio, and Wyoming in the 1860s. In the world, only a handful of countries prohibit the marriage of first cousins. First-degree cousins and first-degree cousins once abducted in Nevada are not allowed to marry, have sex, or live together, but half-cousins are allowed to marry in the state. And who can forget one of the most notorious royal families, House Targaryen? For nearly 300 years, from Aegon I to Aerys II, the Targaryens ruled the Seven Kingdoms and preserved their family lineage through the breeding of incest. Not only cousins marry, but so do sisters and brothers. And even the Lannisters did the inbreeding, but not the actual intermarriages (think Cersei and Jaime Lannister). Illinois first cousins can only marry if both parties are 50 years of age or older, or if one of the parties is barren. However, sexual relations and cohabitation between first cousins are allowed, and first cousins who have been abducted once are allowed to marry. But half-cousins are not allowed to marry, the law says. OK, back to Colorado.
The state prohibits not only incestuous marriages, but also certain other types. Other legal requirements for marriage in Colorado are: Like Maryland, Massachusetts allows first-degree cousins to be removed once, half-cousins by adoption, to live together and have sex. First cousins from Connecticut who want to get married: Rejoice! You can do this under the rule of law. Connecticut also allows first cousins to have sex and cohabitation. First cousins who have been abducted once, half-cousins and cousins by adoption can also marry. According to this law, the following parents are not allowed to marry each other: States have various laws governing marriage between cousins and other close relatives, which include factors, including whether the parties to the marriage are half-cousins, double cousins, infertile, over the age of 65, or whether it is a widespread tradition in an indigenous or ancestry culture, adoption status, In-laws, whether genetic counseling is necessary or not and whether it is permissible to marry a first cousin once it has been removed. Minnesota does not allow first-degree cousins to marry in the state, but allows first-degree cousins to live together and have sex. First cousins who have been abducted once are allowed to marry, but half-cousins cannot marry.
Some news sources then referred only to the provisions on polygamy and child abuse, ignoring the part of the law relating to marriage between cousins, as did some more recent sources.     The new law made sexual intercourse with a first-degree adult cousin a more serious crime than with adult immediate family members. However, this law was amended in 2009; While sexual intercourse with close adult family members (including first-degree cousins) remains a crime, the harshest penalty is now associated with sexual relations with a person`s direct ancestor or descendants.  First cousins may live together or have sex. First cousins and adoptive cousins are allowed to marry. In Colorado, prohibitions are absolute and do not depend on a spouse`s ability to have children or whether the parent is half-blood or thoroughbred. Compare that to some states like Arizona, Illinois, and Indiana, where cousins are only allowed to marry if both are over 50 or if one of them is barren. Because Colorado has no such restrictions, there are occasional reports that the state is a “destination” for first-degree cousins of other states who want to get married.
In Texas, the only relationships with permission to marry are first-degree cousins who were abducted once. First cousins, half-cousins of adoption are not allowed to marry. First-degree cousins in Texas are also not allowed to live together, nor are they allowed to have sex. While some states allow these types of marriages, others do not. In general, laws about the legality of marrying your cousin fall into three categories: Several states in the United States prohibit marriages between cousins.   As of February 2014, 24 U.S. states prohibit marriages between first cousins and seven U.S. states allow marriages between first cousins and seven U.S.
states. States only allow certain marriages between first cousins.  Six states prohibit marriages with first-degree cousins who have been removed once.  Some states that prohibit cousin marriages recognize cousin marriages contracted in other states, but despite occasional claims that this is generally true, there are also laws that explicitly invalidate all marriages of foreign cousins or marriages contracted by out-of-state state residents. [ref. needed] Ultimately, while the law of the place of celebration applies, the exception to the rule becomes a “case-by-case” decision that depends on where the couple will reside in the United States. In all cases where you suspect that the marriage is not valid for the visa decision, contact a qualified immigration lawyer or seek expert advice from the counseling service.  “In addition to the United States, these include the People`s Republic of China and Taiwan, the Republic of Korea and the Democratic People`s Republic of Korea, and the Philippines,” Bittles explains. “Even in the People`s Republic of China, the ban on marriage of first cousins is not enforced in officially recognized ethnic minorities where consanguinity marriage is traditional.” These developments led thirteen states and territories to adopt prohibitions on marriage between cousins until the 1880s. Although at the same time, the eugenics movement did not play a major direct role in the bans. George Louis Arner viewed prohibition in 1908 as a clumsy and ineffective method of eugenics, which he believed would eventually be replaced by refined techniques. By the 1920s, the number of bans had doubled.
 Since that time, Kentucky (1943) and Texas have banned marriage for first-degree cousins, and since 1985, Maine has ordered genetic counseling for cousin marriage to minimize the risk of a serious health problem for their children. The National Conference of State Uniform Law Commissioners unanimously recommended in 1970 that all such laws be repealed, but no state has dropped its ban.    For example, first cousins are not allowed to marry in Michigan, and such marriages in Michigan are considered null and void from the outset. However, a 1973 Michigan Supreme Court decision found that a marriage between first cousins married in Hungary was still valid.