Detection-weighted distribution of effective spin parameter of BH-BH mergers for model M20.B (fallback decreased BH kicks; no BH kicks for massive BHs) and M23.B (high BH natal kicks with 1D σ = 265 km s⁻¹ for all BHs) with Geneva mildly efficient angular momentum transport. We note that both distributions peak at high values (χ_eff ∼ 0.9). Natal kicks decrease the effective spin parameter (average χ_eff = 0.3; M23.B) as compared to model with almost no BH kicks (average χ_eff = 0.7; M20.B). For comparison, we show the 90% credible limits (blue arrows) and the most likely values (blue stars) of the effective spin parameter for ten LIGO/Virgo BH-BH mergers. Although we can recover all the reported values, the predicted peak of χ_eff distribution is not coincident with the current LIGO/Virgo data. It indicates that BHs have typically lower spins than resulting from the Geneva model for BH natal spins, or that the detected BH-BH mergers are not formed in the classical isolated binary evolution.