Long lost ex-step-siblings and reincarnated brothers

My sister's recent Facebook post captures the essence of dysfunction 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 had dinner with my other brother but hasn't even attempted to call me. Really?