Is Generation Two Particles Won't Cancel Regeneration One Particle?

Our first question comes from david smith. He's responding to a conversation we had about annihilation of matter and anti matter. We talked about how electrons, for example, can annihilate with their opposite particle, thepositron. But we commented that a positron can't, for instance, annihilate with a muon - which is like the heavier version of the electron.