Since identical twins occur as a result of the division of one egg, they have the same genetic structure. Therefore, their phenotypes and sex are also always the same. However, due to the effect of environmental factors, some of the characteristics of twins living in different regions appear to develop differently. In our case of 17-year-old maternal twins, we emphasized that nasal pathologies carried a genetic background in terms of their similarity in septum deviation and external nasal deformity, which were determined to have occurred without a history of trauma.

The article has also been presented at 10^th Turkish Rhinology Congress, 22-25 May, 2014 Antalya, Turkey.