During the initial epochs of transfer learning (epochs one to six) the distances of the generated molecules to the target space (MEGx) and the source space (ChEMBL24) decreased before increasing. The lower FCD to the source space during the initial epochs can be explained by the initial effect of transfer learning. The model focused on features that are common between the source space and the target molecules possibly because ChEMBL24 contains natural products, and many synthetic molecules are natural product-inspired compounds . The increasing distance to the natural product target space during transfer learning might seem initially counterintuitive. A likely explanation for this increasing distance to the natural product target space is the limited size and diversity of the set of five natural products used for transfer learning compared to the whole natural product space.