Endogamy in the context of "Recessive gene"

An ethnicity or ethnic group is a group of people who identify with each other on the basis of perceived shared attributes that distinguish them from other groups. Attributes that ethnicities believe to share include language, culture, common sets of ancestry, traditions, society, religion, history, or social treatment. Ethnicities are maintained through long-term endogamy and may have a narrow or broad spectrum of genetic ancestry, with some groups having mixed genetic ancestry. Ethnicity is sometimes used interchangeably with nation, particularly in cases of ethnic nationalism. It is also used interchangeably with race although not all ethnicities identify as racial groups.

By way of assimilation, acculturation, amalgamation, language shift, intermarriage, adoption and religious conversion, individuals or groups may over time shift from one ethnic group to another. Ethnic groups may be divided into subgroups or tribes, which over time may become separate ethnic groups themselves due to endogamy or physical isolation from the parent group. Conversely, formerly separate ethnicities can merge to form a panethnicity and may eventually merge into one single ethnicity. Whether through division or amalgamation, the formation of a separate ethnic identity is referred to as ethnogenesis.

Zoroastrianism, also called Mazdayasna or Behdin, is an Iranian religion centred on the Avesta and the teachings of Zarathushtra Spitama, who is more commonly referred to by the Greek translation, Zoroaster (Greek: Ζωροάστρις Zōroastris). Among the world's oldest organized faiths, its adherents exalt an uncreated, benevolent, and all-wise deity known as Ahura Mazda (𐬀𐬵𐬎𐬭𐬀⸱𐬨𐬀𐬰𐬛𐬁), who is hailed as the supreme being of the universe. Opposed to Ahura Mazda is Angra Mainyu (𐬀𐬢𐬭𐬀⸱𐬨𐬀𐬌𐬥𐬌𐬌𐬎), who is personified as a destructive spirit and the adversary of all things that are good. As such, the Zoroastrian religion combines a dualistic cosmology of good and evil with an eschatological outlook predicting the ultimate triumph of Ahura Mazda over evil. Opinions vary among scholars as to whether Zoroastrianism is monotheistic, polytheistic, henotheistic, or a combination of all three. Zoroastrianism shaped Iranian culture and history, while scholars differ on whether it significantly influenced ancient Western philosophy and the Abrahamic religions, or gradually reconciled with other religions and traditions, such as Christianity and Islam.

Originating from Zoroaster's reforms of the ancient Iranian religion, Zoroastrianism began during the Avestan period (possibly as early as the 2nd millennium BCE), but was first recorded in the mid-6th century BCE. For the following millennium, it was the official religion of successive Iranian polities, beginning with the Achaemenid Empire, which formalized and institutionalized many of its tenets and rituals, and ending with the Sasanian Empire, which revitalized the faith and standardized its teachings. In the 7th century CE, the rise of Islam and the ensuing Muslim conquest of Iran marked the beginning of the decline of Zoroastrianism. The persecution of Zoroastrians by the early Muslims in the nascent Rashidun Caliphate prompted much of the community to migrate to the Indian subcontinent, where they were granted asylum and became the progenitors of today's Parsis. Once numbering in the millions, the world's total Zoroastrian population is estimated to comprise between 110,000 and 120,000 people, with most of them residing either in India (50,000–60,000), in Iran (15,000–25,000), or in North America (22,000). The religion is thought to be declining due to restrictions on conversion, strict endogamy, and low birth rates.

A caste is a fixed social group into which an individual is born within a particular system of social stratification: a caste system. Within such a system, individuals are expected to marry exclusively within the same caste (endogamy), follow lifestyles often linked to a particular occupation, hold a ritual status observed within a hierarchy, and interact with others based on cultural notions of exclusion, with certain castes considered as either more pure or more polluted than others. The term "caste" is also applied to morphological groupings in eusocial insects such as ants, bees, and termites.

The paradigmatic ethnographic example of caste is the division of India's Hindu society into rigid social groups. Its roots lie in South Asia's ancient history and it still exists; however, the economic significance of the caste system in India seems to be declining as a result of urbanisation and affirmative action programs. A subject of much scholarship by sociologists and anthropologists, the Hindu caste system is sometimes used as an analogical basis for the study of caste-like social divisions existing outside Hinduism and India. In colonial Spanish America, mixed-race castas were a category within the Hispanic sector but the social order was otherwise fluid.

The genetic history of Sardinia consists of the study of the gene pool of the Sardinian people with two main objectives. The first is purely cultural and is to reconstruct the natural history of the population. The other instead has the aim of understanding the genetic causes of high life expectancy and of some pathologies by exploiting some peculiarities of the Sardinian population.

The geographical position of Sardinia and the mountainousness of its territory have meant that particular anthropological and genetic characteristics have been created in the Sardinian population, due to phenomena such as isolation, endogamy and evolutionary processes such as genetic drift, in similarly to other European populations such as the Basques, Sámi and Icelanders.

Exogamy is the social norm of mating or marrying outside one's social group. The group defines the scope and extent of exogamy, and the rules and enforcement mechanisms that ensure its continuity. One form of exogamy is dual exogamy, in which two groups continually intermarry with each other.

In social science, exogamy is viewed as a combination of two related aspects: biological and cultural. Biological exogamy is the marriage of people who are not blood relatives. This is regulated by incest taboos and laws against incest. Cultural exogamy is marrying outside a specific cultural group; the opposite is endogamy, marriage within a social group.