Is it or is it not possible to predict "with a fair degree of accuracy" one's nationality through one's handwriting?
Yes, it's possible.
It is possible for a trained expert in handwriting to tell with a fair degree of accuracy the nationality ... of any one who executes writing of any kind. - Disputed Handwriting, 1909: Jerome B. Lavay,
The authors of this 2014 paper develop a handwriting recognition system. Looking at handwriting samples from 8 nationalities (≥ 30 samples each), its system correctly predicts the nationality of the writer 48% of the time (as opposed to a 12.5% random prediction rate).
One webpage states:
Many handwriting experts claim you can’t tell a person’s ethnicity or nationality by their handwriting, but again, I say this isn’t true.
No, it's not.
The published studies on ... nationality ... and their relationship to handwriting have had mixed results.
One webpage claims:
Handwriting cannot tell someone's age, race, gender, religion, nationality, whether someone is right or left handed, and it cannot predict the future.
A graphologist will not be able to determine the nationality of the writer.
This question is motivated by my anecdotal experience that for some specific handwriting styles, it is possible to identify the nationality of the writer, even without any special training or equipment/software. Example: One particular handwriting style (in English) seems to be used only by people from China.