Behavioural biometrics is increasingly considered both for security and non-security related applications. In contrast to traditional modalities such as fingerprint, face or iris, behavioural modalities tend to be much more privacy invasive. Profiling is inherent to the technology itself rather than only a potential secondary activity. Particular user profiles are always at risks to be linked with information from other sources, leading to a large variety of unwanted consequences and long term effects. The usual embedded and hidden collection of data makes it extremely difficult for the affected users to monitor or even control such information flows. Current concepts of data protection like Privacy Enhancing Technology (PET) or Transparency Enhancing Technology (TET) are still insufficient to deal with the arising risks. More comprehensive training about the basic functionality and the potential effects of behavioural biometrics is needed in the absence of convincing technological protection mechanisms.