‘…Among the Battas of Sumatra these laws of avoidance affect all near relationships. For instance, it would be most offensive for a Battan to accompany his own sister to an evening party. A brother will feel most uncomfortable in the company of his sister even when other persons are also present. If either comes into the house, the other prefers to leave. Nor will a father remain alone in the house with his daughter any more than the mother with her son. The Dutch missionary who reported these customs added that unfortunately he had to consider them well founded…