Many companies develop software product lines-collections of similar products-by cloning and adapting artifacts of existing product variants. Transforming such cloned product variants into a "single-copy" software product line representation is considered an important software re-engineering activity, as reflected in numerous tools and methodologies available. However, development practices of companies that use cloning to implement product lines have not been systematically studied. This lack of empirical knowledge threatens the validity and applicability of approaches supporting the transformation, and impedes adoption of advanced solutions for systematic software reuse. It also hinders the attempts to improve the solutions themselves. We address this gap with an empirical study conducted to investigate the cloning culture in six industrial software product lines realized via code cloning. Our study investigates the processes, and the perceived advantages and disadvantages of the approach. We observe that cloning, while widely discouraged in literature, is still perceived as a favorable and natural reuse approach by the majority of practitioners in the studied companies. This is mainly due to its benefits such as simplicity, availability and independence of developers. Based on our observations, we outline issues preventing the adoption of systematic software reuse approaches, and identify future research directions.