Recent research in open and user innovation has shown that users, as well as households, significantly contribute to improving existing products and may even innovate completely new solutions which better correspond to their unfulfilled needs. But many, if not most of these, remain unknown to the public and research on household sector innovation shows that these inventions often fall short when it comes to their diffusion to potential customers. With this study we aim to contribute to a better understanding of the reasons for this lack of diffusion beyond known aspects. To do so, we particularly address and analyze the effect of the perceived product origin on consumer adoption decisions. Based on two randomized experiments within the household sector, building on legitimacy theory, our study reveals significant differences in the acceptance for identical products, dependent on whether they are introduced as pure user innovations or products from an established firm. We can show that pure user innovations cause adoption bias and, therefore, represent a barrier for diffusion in the general population. However, when user innovators employ certain practices, their innovations are significantly more likely to be adopted and are even on par with incumbent products. Thus, user innovators can apply certain legitimacy strategies to overcome this adoption bias. We test variations in these best practices and show how user innovators can stimulate adoption of their solutions. Our findings contribute novel and relevant implications for the diffusion of household innovations, co-creation and user entrepreneurship, and provide avenues for future research."