Introduction: Both of heredity and the environment may play a crucial role in development of a person's handwriting. This study aimed to investigate the degree of similarity in Arabic handwriting of twins and features of Arabic handwriting in relation to some environmental factors.
Methods: The study included 40 pairs of adult Egyptian twins (20 identical and 20 fraternal pairs). The study investigated the effects of genetic factor as well as two environmental factors (primary language of education and drawing practice) on Arabic handwriting of the included subjects.
Results: There was no significant difference between identical and fraternal twins in frequency of similar pairs in the characteristics of Arabic handwriting. Subjects whose primary language of education was Arabic language were found to have better legibility of Arabic handwriting and lesser frequency of spelling mistakes. Also, they showed more frequent use of punctuation marks. On the other hand, handwriting of subjects whose primary language of education was English language showed greater frequency of keeping regular word spacing. Subjects who were practicing drawing were found to keep regular right and left margins, regular spacing between lines and good legibility of handwriting.
Conclusions: Both of primary language of education and drawing practice was found to affect Arabic handwriting while the effect of genetic factor couldn't be evidenced.