Continuity mistake: In the episode where Lois takes revenge on the four girls who pranked Reese, Lois and Reese use a makeshift catapult to launch paint balloons at one of the girls and her date. The first balloon hits the girl, covering her left shoulder with pink paint. In the shot where her date gets hit with a balloon, her shoulder is no longer covered in paint. Some of the paint blotches change size and shape on both her and her date throughout this scene as well.
Other mistake: When it is Dewey's birthday Malcom grabs a piece of the cake. It goes to Dewey then back to Malcom and he is chewing, but there is no bite in the cake.
Answer: It is made up - although it is implied she is Croatian, she never mentions it herself.