This works well a lot of the time, but there are cases where raising a child to be bi or tri-lingual can cause all sorts of problems due to difficulty in acquir

This works well a lot of the time, but there are cases where raising a child to be bi or tri-lingual can cause all sorts of problems due to difficulty in acquiring fluency in at least one language. The problems can eventually manifest themselves as behavioral issues. Working in my field linguistics course, we had to do quite a bit of work with these children. Often times, switching to one primary language at home caused the issue to go away within a few months (for children under a certain age).