  There is a general consensus that the frequencies of the kilohertz
Quasi-Periodic Oscillations (kHz QPOs) in neutron-star low-mass X-ray binaries
are directly linked to the spin of the neutron star. The root of this idea is
the apparent clustering of the ratio of the frequency difference of the kHz
QPOs and the neutron-star spin frequency, $\Delta\nu/\nu_s$, at around 0.5 and
1 in ten systems for which these two quantities have been measured. Here we
reexamine all available data of sources for which there exist measurements of
two simultaneous kHz QPOs and spin frequencies, and we advance the possibility
that $\Delta\nu$ and $\nu_s$ are not related to each other. We discuss ways in
which this possibility could be tested with current and future observations.
