Only rarely have geneticists, neurobiologists and psychologists availed themselves of twins for the study of the human mind's individuality. I believe, on the contrary, that twin data represent an invaluable means of research also for phenomena connected with human individuality and the functioning of the nervous system.

To this end I thought of having MZ and DZ twins take a creativity test by means of spontaneous drawings of a single subject applied to individual MZ and DZ twin pairs.

The preselected twins totalled 31 MZ and 13 DZ pairs of an age span during which the twins live together and experience the same environmental influences.

The creativity test I devised consists of asking the twins to make a drawing of the family mealtime scene at which they all participate. The drawings were to be made on identical pieces of white paper, selecting colors from the same box of colored pencils given to each of them. When the test was explained, each twin was placed in a different room with no possibility of communication, and was asked to make the drawing, supervised at a distance by an assistant.

In order to analyze the drawings, I established ten parameters: 1) First impression at a glance; 2) Choice of colors; 3) Choice of perspective; 4) Choice of persons' positions; 5) Emphasis on twins; 6) Shape of table; 7) Table settings and food dishes; 8) Room furniture; 9) Drawing of building; 10) Landscape.