In this article we introduce the first twin study in Turkey with the future plan to register all twins born in Turkey for research purposes. The Turkish twin study will illuminate the etiology of health problems in the context of cultural differences, owing to the rich cultural diversity in Turkey. As a first step, we selected a sample of 618 twin individuals from 302 pairs and 14 singletons living in the Kirikkale and Ankara regions of Turkey and administered a questionnaire with items about nicotine use, psychiatric disorders, and information about the family, in addition to zygosity items. Our study provides valuable information regarding factors related to nicotine dependence, age, gender, social situation, and family structure.