 Since 1941 he was a full member of Lithuanian Academy of Sciences.Being born as Tadeusz Iwanowski in Lebiodka, Hrodna Voblast of today's Belarus, in a Catholic noble family loyal to the heritage of Grand Duchy of Lithuania, he did not know the Lithuanian language until 1905.Ivanauskas considered himself to be Lithuanian, and dedicated his life to the newly re-established country.