We define and study two mathematical models of a surprising biological strategy where some individuals adopt a behaviour that is harmful to others without any direct advantage for themselves. The first model covers a single reproductive season, and is mathematically a mix between samplings with and without replacement; its analysis is done by a sort of "reverse numerical analysis", viewing a key recurrence relation as a discretization scheme for a PDE. This model is then used as a building block for a variant of the classical Wright-Fisher model. In the large population limit, we prove the convergence of the renormalized process to a diffusion with a frequency dependent drift. This allows a quantitative comparison of the indirect selective advantage with the direct one classically considered in the Wright-Fisher model.