Am I the asshole for having an asshole??

So I shat on my baby sister, she’s 2, and now she has an e CoLI InFEcTion or something. I think she should just grow the fuck up and stop being a puss sour. My parents are saying “how the hell did I think this was okay?” But like bruh it was just a harmless prank. I’m only 35, I make mistakes too 🥺