kill him. wishper " mother, take your son, your elder son, that you loved, and rise him for sacrefice for the lord ".
lol joking.
the main reason for this is Grudge between the brothers. or if that his way to "puke" all of his anger' on his brother.
but mostly, this is very naturly. the big brother, sience his littel brothers are born, have a secret hate for them. most of us push ut deep to ther Subconscious, but sometime it pup out, in way of cursing and beating. its his way to say to you "im the bigger, im the stronger, you wont steal my parents love". its like a pack of wolves, the elder will control the pack, so he have to show his rank to his brothers. so, you dont have realy what to do. he is bigger, and will stay like that for a while. yuo can always pay back when yoounger will be an advantage {lol again}.
talling to his parents will make it worst, fighting back too {they all cause his scummbag brain to react as "he try to steal it from us! my... precious "...
sorry, i just saw the entire LoTR las week, ill be like that for a while... {try it! all of them one after another}.
so, for a summary, taughe life...
in my family its not happaning, cause im the elder {lol}.