Is it wrong that I've made my older brother develop weird habits because I've been kicking him in the shins for 5 years.
Sort of. Why would you kick him in the shins.
He insist on cleaning up the bathroom every time he enters.
It was wrong to kick your brother all of those years. It may have messed him up for the future.
He's been acting up for years.
You seem to be at least part of the cause, and I hope you don't kick him or any other siblings.