Students

The initial data set consisted of 425 samples from individuals who  reported a minimum of three generations of Lithuanian nationality. The  average age of the participants was 53 years. Lithuania is divided in  two main regions (Aukstaitija and Zemaitija), which can be further  subdivided ethnolinguistically into six dialectal groups. We sampled  three groups from Aukstaitija (western (n = 79), southern (n = 67), and  eastern (n = 79)) and three groups from Zemaitija (northern (n = 79),  western (n = 43), and southern (n = 78)) (Fig. 1). All the study participants provided written informed consent in accordance with the Declaration of Helsinki.