  The possibility of determining the neutrino nature is considered in view of
the most recent experimental observations. The analysis combines schemes with
three and four neutrinos.The data on oscillations is put together with that
from the search of neutrinoless double beta decay and results on tritium beta
decay. All solar neutrino oscillation solutions are taken into account. The
sensitivity of the problem on future experimental bounds from GENIUS is
studied. Dirac neutrinos are shown to be unavoidable already at present in some
schemes and the constraints will quickly become more stringent with future
data. The consequences of including bounds from Cosmology on the neutrino
content of Hot Dark Matter are commented.
