Role of self-avoidance in neuronal wiring

•Self-avoidance. Neuronal self-avoidance represent a repulsion system, which is required for preventing aberrant overlap of sister neurites.•Self-recognition. Distinguishing between sister branches of the same neuron (self) and neurites of other neurons (non-self) depends on contact-dependent molecular self-recognition.•Molecular basis of self-recognition. Self-recognition is evolutionarily conserved but mediated by different classes of surface receptors (Dscam1 in arthropods, clustered Pcdhs in vertebrates).•Molecular diversity of Dscam1 and clustered protocadherins (Pcdhs). Alternative splicing and formation of oligomeric receptor complexes contribute to the molecular diversification needed for neurite self-recognition.