“…Early childhood is a period of rapid social preference development and appears to be formative for an individual's social preferences in adulthood (Piaget, 1965;Kohlberg, 1984;Fehr, Bernhard and Rockenbach, 2008;Almås, Cappelen, Sørensen and Tungodden, 2010;Sutter and Kocher, 2007;Sutter, Feri, Kocher, Martinsson, Nordblom and Rützler, 2010;Harbaugh, Krause and Vesterlund, 2007;Bauer, Chytilová and Pertold-Gebicka, 2014;Ben-Ner, List, Putterman and Samek, 2015;Angerer, Glätzle-Rützler, Lergetporer and Sutter, 2015a).…”