双生児にみられる兄弟的性格差異と家庭での取扱い方

双生児研究その二

抄録

The authors tried to clarity in Vol.2 No.2 that there were some personality differences between member of a pair of identical twins (EZ). Some of these differences were reduced to those of elder-brother-like and younger-brother-like characteristics as seen between non twin siblings.
In Japan there is a great difference in the treatment of the child depending upon his position in the family. In this research as attempt was made to study the relationship of the personality differences between identical twins and their treatment by the family in light of the above mentioned fact.
As the first approach the following questionnaire was made.
1. Do you treat the twin differently?
2. Is the order in which baths are taken or the seating at the dinner table strictly followed in your family?
3. Do you treat the elder as the superior?
4. When they quarrel do you arbitrate or scold based on the reason that they are the older or the younger?
5. Which did you feed first during infancy?
6. Which did you bathe first during their infacncy?
7. Which of them do you wake first in the morning?
8. Which do you serve first at meals and at snack time?
9. Which do you call first when you call them at the same time?
10. Which do you introduce first to others?
11. Then there is an important errand to be done which one do you ask to do it?
12. Which do you ask to preform simple errands?
13. Which do you consult about important matters?
14. At the present which do you depend on more?
15. Which do you expect to be more successful in the future?
16. Do the children feel that they are being scolded as the elder or the younger when they quarrel?
17. Do the children feel that that they are treated as the elder or the younger?
18. Are the twins aware that one is the elder and and the other is the younger?
Which member of the twin was treated as an elder brother by the family was determined by totaling the number of times he was mamed in the following 14items-items 1, 3, 4, 6, 7, 8, 9, 10, 11, 12, 13, 14, 15, and 17. The result is shown in Fig. I (x-male, o-female).
Although parents say that they treat the twins in the smae manner, in reality there is a difference.
As the next step 10 items were chosen from the study which has been reported in a previous article. These 10 items were chosen because it was felt that these best differintiated between elder-brother-like characteristics and youngerbrother-like characteristics.
The index of the elder-brother-like characteristic was the number of his elder-brother-like responses to these ten questions. This also applied for yourger-brothe-rlike characteristic for the younger brother.(These items were scored by both members of the twins and by the parent. The total score would therefore be 30.) The results are shown in Fig. II.
The following is taken from Fig. I and II.
Male N-38 pairs
_??_
Female N-30 Pairs
_??_The coorelation between the extent to which treatment by the family differs and the extent to which the fraternal personality differences of the identical twins exists is significant at the 1% level.
Needless to say the treatment by the family is not the only factor in personality development but it appears that the treatment by the family, that is the family system, plays a role in formulating personality.
In addition to the resuits of the questionnaires 6 case studies are reported in the artice.