All the way through the books, we are informed of the genius of Harry’s parents. I could bring you numerous quotes, but I can’t really be bothered right now. But prominent examples are when ProfMac says that James aced his OWLS with no very little effort, not at all like Harry, who managed just one ‘Outstanding’, and when Slughorn repeatedly tells Harry about his mother’s intelligence.
So my question is this. How come Harry, who incidentally also shares minds with one of the cleverest wizards ever, and has two incredibly clever parents, isn’t particularly bright. He’s got some good points, granted, but generally struggles with his schoolwork. For a boy descended from famously clever wizards in the Peverells, have genetics skipped a generation.
Possible answers to this might be that Harry had a lot to deal with apart from his school work. But that wouldn’t fully explain Harry’s lack of genius.