The (1 + (λ, λ)) genetic algorithm is a younger evolutionary algorithm trying to profit also from inferior solutions. Rigorous runtime analyses on unimodal fitness functions showed that it can indeed be † Extended version of the paper [ADK20] in the proceedings of GECCO 2020. This version contains all proofs and other details that had to be omitted in the conference version for reasons of space. Also, we have added a new section which proves the lower bounds.