(1886) Doubravka's date of birth is not known. The only indication is communicated by the chronicler
Cosmas of Prague, who stated that the Bohemian princess at the time of her marriage with Mieszko I was
an old woman. The passage is regarded as tendentious and of little reliability, and some researchers believe that the statement was made with malicious intent. It is possible that in the statement about Doubravka's age, Cosmas was making a reference to the age difference between her and her sister
Mlada. That would give him a basis for determining Doubravka as "old." (The word
Mlada means
Young). It was also found that Cosmas confuses Doubravka with Mieszko I's second wife
Oda, who at the time of her marriage was around 19–25 years old, a relatively advanced age for a bride according to the customs of the Middle Ages. Some researchers have taken up speculative views, such as
Jerzy Strzelczyk, who assumed that ''in the light of contemporary concepts and habits of marriage of that time (when as a rule marriages were contracted with teenage girls) is assumed that Doubravka had passed her early youth, so, it's probable that she was in her late teens or twenties''. Nothing is known about Doubravka's childhood and youth. In 1895
Oswald Balzer refuted reports that previous to her marriage with Mieszko I, Doubravka was married to
Gunther, Margrave of Merseburg and they had a son,
Gunzelin. This view is based on the fact that
Thietmar of Merseburg in his chronicles named Gunzelin, Gunther's son,
brother of Bolesław I the Brave, Doubravka's son. Currently, historians believed that Gunzelin and Bolesław I are in fact cousins or brothers-in-law. ==Marriage and Christianization of Poland==