This paper starts with a brief historical overview of pairing in nuclei,
which fulfills the purpose of properly framing the main subject. This concerns
the pairing properties of a realistic shell-model effective interaction which
has proved very successful in describing nuclei around doubly magic 132Sn. We
focus attention on the two nuclei 134Te and 134Sn with two valence protons and
neutrons, respectively. Our study brings out the key role of one particle-one
hole excitations in producing a significant difference between proton and
neutron pairing in this region