[en] The polarization and differential cross section of ground-state photoneutrons from the reaction ¹⁶O(γ,n₀)¹⁵O at 90^o, have been measured at excitation energies between 17 and 25 MeV. For the first time, a detailed comparison between the polarization of the photoneutrons and the photoprotons (derived from the inverse reaction ¹⁵N(p,γ₀)¹⁶O) is possible throughout the energy range. At energies above 20 MeV, the ratio of the neutron polarization to proton polarization is found to have an anomalous energy dependence. Resonance parameters of E1-M1 parity doublets are given, and the isospin character of the E2 strength is discussed. (author)