Drawing development of identical and non-identical twins: A case study of triplets.

Differences in drawing development are conditioned by genetics, environment and individuality of children. Therefore, it is exciting to observe the drawing development in children, who are raised in the same environment and have a similar genetic basis, that is in twins, triplets, and so forth. In the study, we were interested in the similarities and differences in the drawing development of the triplets, two of which were identical twins (B1 and B2) and one was non-identical (A), and whether the characteristics of the drawing appear more congruently between B1 and B2 than with A. We proposed two hypotheses: H1: There are more similarities in drawings between identical twins (B1 vs B2) than between identical and non-identical one (A vs B1 and A vs B2); H2: The differences between non-identical and identical triplets are less pronounced at the beginning of the drawing development (in doodle phase) and become more distinctive in later development, in drawing of figure and space. We analysed 123 drawings that the triplets (41 drawings of each triplet) drew from 1 to 12 years of age at the same time and on the same topic. The results of our research have shown that both hypotheses can be confirmed. On the general level, there are more similarities in drawing between identical twins compared to non-identical ones; and the differences and similarities become more distinctive throughout the development, especially in figure drawing and in the depiction of space.