Using a Three-item Questionnaire to Determine Zygosity in Chinese Young Twins: A Validation Study

Using questionnaire method to determine zygosity is common in twin research due to its low cost and time saving advantage. A recent study1 by the authors show that a simple 3-item parent questionnaire can achieve accuracy of... [ view full abstract ]

Using questionnaire method to determine zygosity is common in twin research due to its low cost and time saving advantage. A recent study¹ by the authors show that a simple 3-item parent questionnaire can achieve accuracy of over 90% in zygosity classification in a Chinese school-aged twin sample. The three questions asked (1) parental perception of their twins’ zgyosity, (2) twins’ resemblance and (3) whether twins were confused by strangers. The current study attempted to replicate the effectiveness of this 3-item questionnaire in an independent validation sample. Three methods were employed to evaluate parental report accuracy, namely summed score, logistic regression, and decision tree. All three methods yielded similarly high classification accuracy in both the original sample and the validation sample. Furthermore, the current study explored the possibility to improve the questionnaire by adding additional physical characteristics items, such as twins’ similarity in hair texture. How parental responses were affected by the advice of medical professionals and information about the placenta was also discussed.

1. Ho, C. S. H., Zheng, M., Chow, B. W. Y., Wong, S. W.,Lim, C. K., & Waye, M. M. (2017). Adequacy of using a three-item questionnaire to determine zygosity in Chinese young twins. Behavior Genetics, 47(2), 244-254.