How do you get along with your brother/sister?

I have a half brother and half sister I admire, but they "love me but they don't like me". I'm like the defective child. My half sis did help me get to my surgeries when I had cancer, but she won't text me back if I ask how she is. They're 11 and 9 years older than me with a different Mom. They very obviously like to keep their distance from me.