小指甲跟本和民族無關，遍佈西歐大小國家，東南亞、非洲也有。

https://www.ncbi.nlm.nih.gov/pmc/articles/PMC4908446/

A hereditary dysplasia of the fifth toenail identical to our observations was first published in 1969 [1]. Surprisingly, descriptions of a double little toenail are rare [2,3], despite its relatively common occurrence. It was thought to be a feature of Han Chinese [3], but among our patients, there was just one Han Chinese colleague who showed his feet during an observational stage. However, double little toenails were observed in dermatological practices in Germany, Norway, the Netherlands, Switzerland, Belgium, Portugal, and Thailand as well as in immigrants from a variety of other countries including Africa (Benin). Thus, this is certainly not a special racial or ethnic feature, although it has to be stated that our results do not allow conclusions to be drawn as to the frequency of double little toenails in different countries, continents and races.