The effect of religious, cultural and social identity on population genetic structure among Muslims in Pakistan.

Knowledge of historical demography and contemporary social stratification can be valuable in understanding disease patterns, including genetic disorders, especially in communities that have a high prevalence of endogamous and/or consanguineous marriages. This paper provides a background to the religious, historical and socio-cultural factors that have helped define the bounds of endogamy for Muslims in undivided India and more specifically since the creation of Pakistan. The preference for endogamous marriage is based on the clan-oriented nature of the society, which values and actively seeks similarities in social group identity based on several factors, including religious, sectarian, ethnic, and tribal/clan affiliation. Religious affiliation is itself multi-layered and includes religious considerations other than being Muslim, such as sectarian identity (e.g. Shia or Sunni, etc.) and religious orientation within the sect (Isnashari, Ismaili, Ahmedi, etc.). Both ethnic affiliation (e.g. Sindhi, Baloch, Punjabi, etc.) and membership of specific biraderis or zat/quoms are additional integral components of social identity. Within the bounds of endogamy defined by the above parameters, close consanguineous unions are preferential due to a congruence of key features of group- and individual-level background factors.