Reception Class b/g twins- issues with DS

[doublemuvver]

My b/g twins have just started reception, big inner-city primary. They are in the same class (figured this would be OK for reception, plan to separate them from Y1). Both doing well, teacher says they are very bright. DD doing better (more stars, better behaviour) Teacher spoken to us a few times now about DS "answering back" and rude attitude and aggressive behaviour/fighting games at break times. He says he hasn't got any friends (he does, but doesn't always want to play with them), says that no-one likes him. DD has made lots of friends. Is this twin anxiety as they move into separate spheres? Teacher says not to worry too much. At home he is a little mischievous but generally a good, happy little boy. They were both in nursery part-time and had no major behaviour issues there. Wonder if anyone has any thoughts?

Didn't want you to go unanswered. Do you often find that they take it in turns to play up? I know mine do. Also, boys can react quite differently to new situations. I don't think it's uncommon for boys to act up like this when they start school anyway. I'm sure it will be fine. Can you try to arrange a playdate for him?

do the classes generally move around at the start of yr1?
if not then moving classe may not be a possibility

is he jealous of his sister and acting up?

if he sees her being rewarded and he isn't he may not quite understand why this is happening, especially if the norm is that they both get treated at the same time

I'm a g/b twin and my brother was not as academic or had the attention span when we started school (caught up by end of primary) and he used to get very annoyed when I would do something easily that he struggled with

he didn't realise that was the problem at the time but it didn't take long for my mum to figure it out :)

Thanks for the comments, a better end to the week so fingers crossed it's just a settling in thing