I have 4 Siblings (1 brother, 2 step-brothers 1-step sister) and have a very distinct relationship with each.
I absolutely despise my brother, he is one of the most vile men I have ever met and as awful as it sounds, if I could travel back to 1996 and cancel out his creation and following birth, I would. Everyone in the family (from siblings to grandparents and aunts and uncles) are no contact with him, so that tells you what type of human being he is. The only one who tolerates him (much to everyone bafflement) is my mother and it's probably due to the fact that he is an agressive and abusive prick who refuses to move out and can be quite scary when mad.
He has no notion of money or responsibilities and if my mom dropped dead tomorrow, the reality is that he would be both homeless and in debt, the only relief I have is that I live far far away from him and as a result he will absolutely never be my problem.
DSB1 on the other hand I adore, he is the sibling that is the most like me (despite only sharing half of my genetics) and he was always the calming force, we only had 1 fight in the entire history of our childhood and I cried, because it was unexpected. I live abroad so don't see as much of him as I would, but we are in touch and I really enjoy the young man he has become and we are considering doing some business venture together in coming months/years. He is the first sibling I would call for help if need be and the only one I truly trust.
DSB2 is a young teenager still, so it's hard to gauge how close we are but he was the youngest until a couple of month ago so I will say I do love him as such and try to have a great bond with him, due to having lived abroad most of his life, I do spoil him a bit when I see him which I think he appreciates and I always make sure to spare time for him whenever I can and when I am there, we are quite bonded despite the distance as I am the first one he called to talk to me about his first girlfriend and other delicate topics, which surprised me but also made me very happy. I am intending to take him on a trip of a lifetime once Covid is over (like I did with DSB1 last year).
DSS- She is a baby and I haven't met her yet. Due to Covid I will probably only meet her when she is 2 and between me living abroad, the age gap (more than 20 years) and the fact that I don't get along with my mother and know very little about her dad (despite him being married to my mother), the chances that we'll develop any kind of meaningful relationship is very slim. I assume she will grow up to be this young woman I know is kind of related to me but might only see at funerals and important family events I'll attend. The idea that she will be half my age when I am 50 horrify me for some reason (can't imagine I'll be the type she'll want to hang out with then and pretty sure I won't want to be reminded of my long-gone youth, any more than necessary.) I had always wanted a sister so it's a shame, but we'll see. Life might turn out differently than I expect after all.
Having siblings has confirmed for me that wanting another child just so your first one isn't lonely is bullshit, I am the oldest one, only have a year difference with my brother and I still resent them from bringing him about. He didn't add much to my life and actually would have been quite happier without him making my life hell. And I love the rest of my siblings and wouldn't swap them if I could but I also know I would have been totally happy without siblings and actually probably would have had a much better relationship with my mother as a result.