can you please tell if yuuki and kaname are really siblings? because somewhere i read that kaname is adopted child! and also that he is living for 1000s of years!! i dont get it!

yes I've watched all of vampire knight and red the manga yes kaname and yuki are siblings but I recommend you should read the manga
(I hope this was helpful)

Yes Yuuki and Kaname are siblings

Yuuki' REAL brother was killed sa pamamagitan ng Rido (Kaname & Yuuki' uncle) when he was just born and had Kaname,her ancestor' soul placed in his body.Their parents,despite already figured out that wasn't their son,still took him in and raised him as their own.

So Kaname is both Yuuki' brother,but not.

Since Yuuki was still little and/or not present at the time she never knew her real brother was killed till later on she drinks his blood,looks into his memories or something like that.