I feel ya. My little brother, who out of all of my siblings, is THE MOST RELATED TO ME. (Bc i have two stepbrothers, one stepsister, one sister but she has a different dad) and he ducking- Smears his poop all over his room, and he KNOWS how to wipe and stuff, apparently it's a 'sensory' thing, and he's doing the THING where when you say "No" he beats the crap outta ya, and let me remind you, this is an 11yr old. Yes he is Autistic and has ADHD, but even I'd know not to beat the shit out of people, he attacks the dogs and cats, he attacks our parents and my sister. I have a few scars from him, my parents treat him like a king usually.