You need to parent each kid as they come, OP. Perhaps your others will need to work harder. My firstborn has learning disabilities and needed to work ten times more than the average. My second is gifted and in 10th grade, has just realized this year that homework is a thing, mainly because she's taking AP Calc BC and AP Physics C together
You can provide enrichment at home and please, please, focus on extra-curriculars such that your kid attains a high level by 12th grade. They will count for college admissions.