My youngest brother Jackson acts strange

[JsBigSis]

Well I was just wondering if there is a certain reason for my youngest brothers behavoir. He is a truly sweet little boy he, and his twin, had just turned 10 a couple days ago but Jackson always has acted strange. There are four children in our family Me, I am the oldest I am 14; Taylor who is 12 and the boys Garrett and Jackson who are now 10. Our parents are currently married. Well now to actually tell you what he does. He used to have meltdowns at school, he is very smart but he would make comments about people like "Finally and Took you long enough" who took a long time at th board doing little problems. When the teacher would confront him he would say he didn't deserve to get introuble because everyone was thinking that person took to long.
He tells his peers who didn't immediatly like him that he doesn't like him, which I think he says that because he doesn't want to be hurt doubley if he did like them and they hurt him.
When ever he gets sad or upset in anyway he runs off to his room and hides under his bed or stuffs his head in pillows.
He acts somtimes like a cat when he is around me, he rubs his cheek against my arm or face, or he sort of bits me. Which I just think is from when they were little my mom would play with them like that and he just doesn't want to relive some of those good times, not like we don't have any now.
And it seems like he has only a few main interests at all. Wizards101,Baseball, and Sonic the hedgehog. It is amazing the way him and his twin interact. They are just so much a like in everything.
I would just like to know if that is normal behavior for a boy of 10? And if it isn't is there anyway to change it. And I am fully aware this would be my parents buisness but I think I am old enough to see the stuff that goes on in Jackie's life.