  One fundamental goal of the newly born gravitational wave astronomy is
discovering the origin of the observed binary black hole mergers. Towards this
end, identifying features in the growing wealth of data may help in
distinguishing different formation pathways. While large uncertainties still
affect the binary formation models, spin-mass relations remain characteristic
features of specific classes of channels. By focusing on the effective inspiral
spin $\chi_\text{eff}$, the best reconstructed spin-related merger parameter,
we show that current GWTC-3 data support the hypothesis that a fraction of
events may display mass-spin correlations similar to one expected by dynamical
formation channels of either astrophysical or primordial nature. We quantify
the Bayesian evidence in favour of those models, which are substantially
preferred when compared to the Gaussian phenomenological model adopted to
describe the distribution of $\chi_\text{eff}$ in the recent LIGO/Virgo/KAGRA
population analyses.
