The creation of digital replicas of individuals, based on their data, gives birth to what experts in medical field called the ‘personal digital twin’. This new ‘digital self’ raises many difficulties, in sociology, in science and in law. This article presents the main issues from a legal point of view. Most of the structuring concepts of the law are questioned by these special symbiotic systems: the concept of person, identity, entitlement to rights and obligations, legal capacity, liability, data processing, etc. All these notions, which are rooted in the legal tradition, are correlated to the human person and must therefore be profoundly adapted to apply to the digital twin. It is a new experience: the law must devise concepts to take account of an entity that is halfway between people and things. We see this as an opportunity to rethink the legal framework and to consider the advent of future digital human rights. This questioning, barely sketched here, aims to make the law evolve towards a better consideration of symbiotic systems. This article is part of the theme issue ‘Towards symbiotic autonomous systems’.