Marauders aren’t’ stupid :
• James is a little prick that is quite good at a lot of subject but he only master the ones he actually likes
•Remus need to study to have good grades he’s clearly not gifted but manage to have the best grades
•Pete got anxiety so it’s really complicated for him to work, if he got motivation and is in the mood to work he will neglect all his body’s basic need until it’s done
• Sirius seem like the one who never work, people never saw him open a book to study a new subject, at one point peter was really curious because this b*tch have one of the best grades of the class and that is not possible. So he just ask the question one day and Sirius is surprised because « didn’t you study the school program when you were a kid ?” And James Peter and Remus are so confused because wtf.
But yea basically Walburga stole sirius and Reggie’s childhood by making them learn all the fcking program in advance and because she’s such a great mom sirius had no choice than to know word by word every subject so yea this man isn’t a genius he’s just a children that try to survive and make his mother proud.