Long lost ex-step-siblings and reincarnated brothers

This recent Facebook post by my sister captures the essence of dysfuction that consumes my family perfectly:

So my ex-step-brother, who I haven't seen since our parents divorced when I was seventeen, friended and messaged me on Facebook. My biological brother, who went into hiding for several years and was presumed dead, has resurfaced and has had dinner with my other brother hasn't even attempted to call me. Really?