Aim: The purpose of the work was study of the influence of genetic and environmental factors on the formation of classic smile parameters. Materials and Methods: Research was conducted on 12 people (6 pairs of (MZ) twins): 4 pairs of females and 2 pairs of males. The age of the patients was 17-28 years. Results: In (MZ) twins, the criteria for an ideal smile coincide in 51.6% of cases, do not coincide in 26.6% of cases, there are no criteria in 21.8% of cases. Genetic factors have a significant influence on the morphological features of the teeth, because more than 50% of the parameters of an ideal smile in (MZ) twins are coincided. Conclusions: Signs of external similarity in (MZ) twins, taking into account such morphological characteristics as the set of the eyes, the shape of the nose, lips and teeth are confirmed by photo documentation and biometric research methods. However, the ratio between lips, teeth and gums when forming a smile in (MZ) twins is the same in 51.6% of cases. Based on the results of this study, we cannot confirm the primary role of genetics in dental features such as the ideal smile criteria. Environmental factors (nature of nutrition, bad habits, sucking, tooth extraction, sleeping on the stomach, etc.) and traumas have a significant influence on the features of dental smile parameters.