Summary: in the Hoklo language, grandchild and nephew/niece share the same term. This coincidence is not only observed in Hoklo, but also in a wide range of languages in Southeast Asia, including various Tai languages, as well as in modern Vietnamese ("cháu"). This phenomenon is likely to be inherited from the ancient Yueh (Bai-Yue) civilization.

From: Japanese/Austro-Tai: Paul K. Benedict, 1990 ISBN 0-89720-078-0 (page 140)

In an early (1967) study of Austro-Tai kinship terms (Benedict 1975:65-74), the writer pointed out that a 'skew' in hte Tai terminology, with 'nephew/niece' equated with 'grandchild' (P-Tai *hlaan -- F.-K. Li 1977:137), is to be interpreted as reflecting an original 'skew' in the reciprocal 'uncle/aunt (parents' sibling)' and 'grandparent' terms for his parents- in-law (=uncles/aunts under cross-cousin marriage rules). Both Mak and Mulao, in the Kam-Sui group, show the Tai 'skew' and, as emphasized by the writer (1975), in Mak the term (laan) is also applied to a cross-cousin: father's sister's daughter, as in the phrase: ?a:u laan 'to marry a father's sister's daughter (very common)' (F-K. Li 1943 - writer's translation.) In the same study the writer pointed out that the Oceanic (Martin 1979) and Fijian shift from 'grandparent' to 'mother's brother' in the basic P-Austronesian *?a(m)pu etymon can be viewed as part of the same over-all picture on the vast Austro-Tai canvas, with the Fijian (Bau, Nadrau) prescribed marriage with father's sister's daughter corresponding precisely to the Kadai (Mak) pattern. He concluded (1975:71-2) that his analysis 'strongly suggests that an archaic kinship system with very specific features, as delineated above, underlies the present terminologies found in this broad area.'

This was extremely far-reaching conclusion, indeed, even for the writer, but some support has now been found for it, in part from the Japanese-Ryukyuan evidence, in part from the extensive Austronesian data that has been marshaled by Blust (1980c)....