  We study the influence of lepton flavour asymmetries on the formation and the
mass spectrum of primordial black holes. We estimate the detectability of their
mergers with LIGO/Virgo and show that the currently published gravitational
wave events may actually be described by a primordial black hole spectrum from
non-zero asymmetries. We suggest to use gravitational-wave astronomy as a novel
tool to probe how lepton flavour asymmetric the Universe has been before the
onset of neutrino oscillations.
