is this inappropriate brother/sister behaviour?

Not really sure where to start with this, but basically Im really close to my family but physically we dont really hug or touch at all.

Now, I know its normal to hug your family, kiss on the cheek etc when you greet them, but Im a bit concerned about my boyfriends relationship with his sister.

(Id like to make it clear that Im not saying any of this out of jealousy, I just genuinely want an idea of what is normal to other families, because to me, this is strange).

He hugs her for prolonged periods of time, and they will just stand hugging with their eyes closed for a good few minutes. Also, when im there, he will hug her from behind, play with her hair and hold and stroke her hands. We went out to a family event, and he sat next to her on the sofa, put his arm round her and they started looking at each other rather lovingly. Ive seen him sit with her half on his lap with her head buried in his chest, cuddling and playing with her hair.

I dont want to over react (which i probably am), but personally i would find this uncomfortable!
Is it normal? Do other siblings do this with each other?

I have three younger brothers, Im 24 and they are 23, 22 and 20 respectively. I would find it seriously uncomfortable if any of them stroked my hair/hands.. Maybe it's just the way they've been brought up though?

Are you kidding me?..I think it is perfectly normal...common.......my sister just walked into my room a minute ago half naked...she is in her thirties....I am in my mid twenties......who cares......we have a very playful relationship.......it doesnt matter....until you see him stick his tongue in her mouth...or until you see him stick his " you know what" into her " you know what", I think it shouldnt bother you......

Are you kidding me?..I think it is perfectly normal...common.......my sister just walked into my room a minute ago half naked...

What do you mean 'half naked'? Like, underwear?

May I add, your use of ellipses in that post is excessive.

Mormon?

Yeah...I know it is excessive....I obviously do that a lot.......

Anyways...yes....half naked..as in just panties and a top......

Guess what?..my "dick" wasnt hard.....LOL....it is all in the head........Although she is very playful...so I understand that is just how she is..........it doesn matter.......

As she walked in..I jokingly said " Mennnn, what are you doing...why are you walking around the house half naked"...her response ..."what? are u turned on"?......jokingly....you get the gist... I just ignored her and continued my work on my computer......it doesnt matter...I t just depends on the type of relationship the siblings have with one another.....an No!! I am not a mormon.....

If you're both comfortable with it then there's no problem, I just cannot imagine ever walking around in my underwear in front of my brothers.

Are you kidding me?..I think it is perfectly normal...common.......my sister just walked into my room a minute ago half naked...she is in her thirties....I am in my mid twenties......who cares......we have a very playful relationship.......it doesnt matter....until you see him stick his tongue in her mouth...or until you see him stick his " you know what" into her " you know what", I think it shouldnt bother you......

Are you kidding me?..I think it is perfectly normal...common.......my sister just walked into my room a minute ago half naked...she is in her thirties....I am in my mid twenties......who cares......we have a very playful relationship.......it doesnt matter....until you see him stick his tongue in her mouth...or until you see him stick his " you know what" into her " you know what", I think it shouldnt bother you......

Just to be clear:

That's really disturbing.