(Phys.org)—A small team of researchers affiliated with the University of Missouri and the University of Nebraska has found that cross-cousin breeding among the Yanomamö people in the Amazon rain forest is beneficial to the parents of young people who wed due to arranged marriages. In their multi-year study, the team describes how they conducted a genealogical study of over 5000 people over the course of 30 years to learn more about Yanomami culture and the impact of cross-cousin marriages.