endogamy
noun [ U ] social science specialized uk/enˈdɒɡ.ə.mi/ us/enˈdɑː.ɡə.mi/
内婚，同族通婚
the fact or custom of having marriage only between members of the same group
Village endogamy is still common in the region. 在这个地区同村通婚仍然是一个很普遍的现象。
Compare: exogamy