In the quest for translation universals, the status of interference has remained unclear. First, it is often indistinguishable from transfer, which blurs the concept of source language or source text influence on translated text. Second, it has been posited as either contradicting universals (Baker 1993), or as a universal, or a major translation in itself (Toury 1995). This paper tackles these issues in the light of corpus data from the Corpus of Translated Finnish (CTF). It also offers a methodological path forward to comparing the relative distance of different corpora from each other, which is crucial for testing hypotheses concerning universals of translated language. The method is used for comparing the overall amount of transfer-like features in corpora from individual source languages, as well as from a mixture of several source languages.