The Dutch language, previously the majority language spoken by the inhabitants, and the official language of Flanders, are the official languages in the area. However, St. Genesius is in severe linguistic flux, as, of the very few municipalities in Belgium not overwhelmingly either French or Dutch-speaking, it is one of the most evenly divided between the two languages. A relative majority of its present residents are Francophone, albeit only by a small amount. As in several other municipalities on the periphery of Brussels, in the 1960s linguistic facilities were given to local French-speaking residents. These mostly stemmed from Francophone workers employed in the neighbouring Brussels migrating to the area. These 'facilities' allow them the right to obtain and submit official documents from the local administration in French, as well as to conduct business with the authorities in the language of their choice. The regionalization of Belgium has maintained that compromise, though politicians representing French-speakers have interpreted these facilities as a permanent right for Francophones in the Brussels periphery. The Flemish viewpoint is that these facilities existed temporarily in order to assist those French-speakers who already had come to live there, to better integrate in the Flemish region, and eventually learn the Dutch language.
Today, this particular municipality remains a controversial topic of local and national politics. A considerable number of Belgian French-speakers would like to see it integrated into the Brussels Capital Region, thus creating a common border between Wallonia and Brussels, as a consequence of the majority of residents who are Francophone. Politicians such as Elio Di Rupo counterpose this in response against Flemish demands to the extension of regionalisation to matters that are still administered federally. The reassignation of the area is strongly opposed by most Flemish people, their politicians and their institutions, who argue that the borders of Belgium's regions, like those of member states in the USA, should not be changed simply because many people move from one state to another. They see the incorporation of the territory into the Brussels as a threat to the language and cultural rights of Flemish residents, and that a precedent could be set that would invite further Francophone migration to other municipalities with facilities. They also view this tendency as the extension of an already prevalent Francophone influence on the capital region. Conversely, some Francophone politicians regard the proposal as best protecting their language rights - the extremist Flemish party Vlaams Belang proposes the withdrawal of these facilities and imposition of Dutch as the sole language of the area. Likewise, the most extremist Francophone party FDF encourages French speakers to never to use the Dutch language anywhere in Belgium, in order to make Belgium French again, like a few centuries ago. The population of the town, however, would not want the regional borders to be tampered with. Most of them chose to live in Flanders rather than Brussels for various reasons, such as lower taxes, lower crime, and lower corruption, and fear that handing their town over to the government of Brussels would force them to move again. The same sentiment is felt in other towns with facilities.