The research used data from 8,500 teenagers of Flemish, Moroccan, Turkish, Polish and Central African descent.
Of the Flemish youngsters one in ten started secondary education in a B class that prepares pupils for vocational training. Among Turkish and Moroccan youngsters the figure was twice as high. It was also higher than the figure for youngsters from other non-Flemish backgrounds.
Earlier research revealed that religion too plays a role.
Whether or not a pupil's mother is in work or not can also have an impact. 83% of Flemish youngsters with an unemployed mum end up in an A class, whereas for Moroccan and Turkish youngsters the figure is around 60%.
The research also indicates that earlier school results have little impact. Even with similar school results children of Moroccan and Turkish descent have a greater chance of ending up in a B class.
An explanation is not immediately clear. Moroccan and Turkish parents may have more limited expectations or pupils may follow the example of friends. There is an important role to play for primary school teachers. The research claims that all too often teachers have middle class views and believe that children from a middle class background will be able to cope in an A class.