In 1960 she married Venezuelan engineer Luis Rosales; they raised five children—Luis, Juan, Sarunas, Rimas, and Saulius—in a multi-lingual household, using both Spanish and Lithuanian.

[3][4] Rosales published studies in the United States, Spain, Venezuela, and Lithuania supporting the idea that the Goths were a Baltic, not Germanic people.

Rosales traced her research on the controversial hypothesis back to 17th-century Prussian scholar Matthäus Prätorius who is thought to have first proposed the idea, which was supported by several Lithuanian historians including Simonas Daukantas and Česlovas Gedgaudas as well as linguist Kazimieras Būga.

[6] Professors Alvydas Butkus and Stefano M. Lanza make similar criticisms of her methodology, to the point of accusing her of twisting the meaning of sources and using "nonexistent" Lithuanian words.

[7] In response to Butkus and Lanza, de Rosales pointed out they lacked depth of knowledge when analysing her texts and that they only focused on one page of the book, ignoring the rest.