Brangäne family asteroids must have surfaces covered with regolith. The observed family (green) in the proper semimajor axis a_p versus the proper eccentricity e_p exhibits a depletion of small bodies in the centre. The synthetic family (blue) was initially more compact. After about 60 My of orbital evolution, it exhibits the same depletion due to the YORP effect (Vokrouhlický et al. 2006). The value of thermal conductivity was assumed low, K = 10⁻³W m⁻¹ K⁻¹, corresponding to regolith. An alternative model, assuming iron composition and no regolith (K = 40 W m⁻¹ K⁻¹), was excluded, because small bodies were not depleted, but spread due to chaotic diffusion in e. A suppression of the YORP effect was also excluded, because small bodies drifted towards small a, due to the seasonal variant of the Yarkovsky drift. The offset of (606) Brangäne with respect to other asteroids is most likely due to a random close encounter with (4) Vesta.