to think this is quite controlling behaviour?

[CarlPoppa]

I feel my brother in law can be very controlling of my sister. He seems to have it in his head that she is going to cheat on him (she hasn't and never would). He is just paranoid. There have been many incidents where I've been very about his actions and comments.

As a family we stayed at my mothers this weekend, I offered to do my sisters hair. We weren't going out, we were just doing it for fun.

Brother in law walked in and saw my sisters hair in curlers and was very and was like -

Why are you doing that to her hair?

Why don't you do it to your own hair?

It wasn't said in a curious way, it was more a disguised accusation.

Would you say this was controlling?

No. He obvs didn't like how you'd done her hair and wondered why you'd done it to her and not to yourself. Maybe he thought you were testing some odd hairstyle on her instead of yourself.

Certainly very weird. How did your sister react? I think the question in itself could be innocent, or just a bad day, but if he often disapproves of things she does, then yes, that's controlling.

He obvs didn't like how you'd done her hair and wondered why you'd done it to her and not to yourself

Surely it shouldn't matter if he likes it though? Should only matter if she likes it?

And she still had curlers in so I hadn't finished.

On it's own, it's not controlling. It just sounds like grumpy git behavior.

It depends what happened next really.

This example in itself doesn't sound particularly controlling but I suspect there are lots of other red flags?

Or prattish. Could be either.

Did she just let him say that? How rude! I'd have had to tell him to fuck off OP. I'd have said "Erm...she can mention it if she's not happy about it love...do you imagine I've held her down or something?"

What a tit.

I suspect there are lots of other red flags?

Definitely. I don't want to say too much because my business to say.

But the comments he's said to me, like he wouldn't like her to gain weight.

He often insinuates that I'm fat and eat unhealthy. I ate a grape in front of him once and he announced that it was healthiest thing he's ever seen me eat.

He seemed like when I said people say me and sister look alike and she agreed.

It's quite weird of him to quiz you about it rather than speaking to her for a start - is she not even allowed to speak for herself?

It's difficult to say on so little information. Being worried that she'll cheat could come from having been cheated on himself. Could be because he's cheating and feels guilty. Could be because he's desperate to keep control of her.
Also the bit about him being shocked that you and your sister look alike - that's just rude!!
I'd say if she seems frightened of him - of his reactions, of upsetting him, it's probably something to worry about. If not just keep an eye to see if things change.