Mother tongue

https://www.parentcircle.com/clipbook/teach-kids-importance-of-mother-tongue/#:~:text=Learning%20to%20speak%20in%20the%20mother%20tongue%20is,and%20aids%2

Learning to speak in the mother tongue is very important for a child’s overall development. Being fluent in the mother tongue, which is also known as the native language, benefits the child in many ways. It connects him to his culture, ensures better cognitive development, and aids in the learning of other languages.

The mother tongue is essential for the development of a well-balanced adult. It plays an important role in the psychological and identity construction of the child. To lose one's mother tongue can cause the loss of  one's profound identity. However, it is a difficult subject to deal with and opinions are divided
Most experts'(psychiatrists and paediatricians) advise parents against educating their children in a language that is not their mother tongue because of the affective link conveyed by the mother tongue
However, the transmission of our ancestors can be painful. The trans-generational process brings us both good and bad. I refer to Anne Ancelin's book "Aïe mes aïeux" which deals with transgenerational links, family secrets, birthday syndrome, transmission of traumas and the practice of the genosociogram
When school rejects the child's mother tongue it rejects the child. Children leave an important part of themselves - their identity - at the door of the school.
However, paediatricians recommend school at 2 years old in disadvantaged environments because the acquisition of the official tongue will be better and richer. In this case the child may be superior to his or her parents because he or she has a better command of the official language. He can help them with administrative problems but unfortunately he can become a little tyrant very quickly.  
Paediatricians and teachers see it as a way to combat school failure.However, these are only points of view. Each child has his or her own story