Another strawman argument. I never said anything about biology. Adoptive parents are still parents. Your siblings are still your siblings.
It’s still different than a child someone considers as “not theirs”.
And btw you were a child, you weren’t ready for that kind of responsibility and shouldn’t have had to do those things, and I’m genuinely sorry that you had to experience that, and I’m glad your siblings had someone in their life to look out for them. I’m sure that made all the difference to them.