We first investigate to what extent natural or degree-preserving crossovers generates novelty. To this end, we use a small random seed set from the USPTO-10k "clean" dataset, a repository of patented molecules introduced in , and ask whether the crossover products are still contained in this data set. Using 1, 5, or 10 starting molecules (shown in Additional file 2) yields 5412, 94636 and 431568 unique molecules, respectively. The test was performed by converting the crossover products to canonical InchIs . Only 4, 19, and 39 recombinants were recovered in the USPTO-10k database. The use of InchIs also accounts for the resonance structures and tautomers. In order to visualize the distribution of parent (USPTO-10k) molecules and crossover offspring molecules we computed 2048-bit Extended-Connectivity Fingerprints (ECFP), a bit-vector representation of structural features in molecules including the circular substructures of each atom in a radius of 2 and performed a t-stochastic neighbourhood embedding (tSNE) . Fig. shows that the offsprings cover a much wider range also in terms of fingerprint descriptors.