Do I really have to reach out to my half siblings anymore?
Why would you want to reach out to them? Have they been in your life before? Seriously, have they?
Because I'm an only child and want to find out if anyone else has my unique qualities. I think this would be the second or third time I have tried to do this.
It can be hard to get to know your half-siblings but it is good that you want to do it. Having family means having more people to care about you.
Yeah I was going to meet with them, but they canceled out on me.
You are a good guy for wanting more family connections and trying your best to get your half siblings to get together with you. If they keep cancelling then I would give up, they might just not have their wits about them enough to be caring.