That’s childish. If it’s only circumstance that’s come between you, there’s no reason to treat them poorly.

One day you might need them.

Why would you dislike someone you don’t know. If you don’t want to meet them, don’t, but you might find that you like them if you give it a chance.

You are not required to associate with people whom you don't like just because you accidentally share some DNA.

I'd say always keep an open view on things. Perhaps they didn't know you because of other circumstances other than not wanting to know you. Anyway, best of luck with this.