Human identity has been examined through biological, psychological, neuroscientific, sociological, and philosophical lenses, each contributing substantially. Contemporary integrative models, most influentially the biopsychosocial framework, propose that these levels be considered jointly, but have been criticized for specifying that multiple domains matter without specifying how they interact. This paper proposes the General Theory of Embodied Identity (GTEI), which holds that identity is not an object a person possesses but a process the organism continuously regulates, arising through the ongoing interaction of four domains: Biological Identity, Regulatory Identity, Psychological Identity, and Social Identity. The distinctive claim is the second of these. Regulatory Identity denotes the characteristic manner in which an individual detects, interprets, and responds to shifts in internal and external conditions, and the capacity to return to baseline afterward. Drawing on work in autonomic regulation, interoception, allostatic load, and interoceptive inference, the paper argues that self-regulation constitutes a measurable interface through which social experience becomes biology and biological state becomes psychological experience. A second construct follows from the first. Cross-domain congruence, the degree of correspondence between a person's domains and in particular between self-reported and physiologically measured state, is proposed as an index carrying predictive weight independent of the level of any single domain. This is the framework's most testable claim and its least supported; the paper specifies both how it might be operationalized and the psychometric obstacles that operationalization faces. The framework is offered as an organizational proposal rather than a claim to new mechanism. Candidate measures and explicit conditions for disconfirmation are specified, on the view that an integrative model which cannot be wrong is not worth adopting. This is the individual-scale paper in a programme examining self-regulation across scales, alongside The Regulatory Singularity (https://doi.org/10.5281/zenodo.21781652) at civilizational scale, The Capacity Era (https://doi.org/10.5281/zenodo.21789658) at institutional scale, and The Playing Zone (https://doi.org/10.5281/zenodo.21790667) across six domains of human function. This manuscript is a preprint and has not been peer reviewed. Version note: Substantive revision to Section 6 and Figure 1. The framework now distinguishes between the cultural supply of narrative repertoire and the regulatory constraint on narrative sustainability: culture supplies the range of narratives available to a person, while regulation constrains which of them can be sustained, revised, or acted upon. Figure 1 adds a direct bidirectional pathway between the social and psychological domains, representing the production of meaning through language, discourse, and relationship without mediation by physiology. Section 3.2 has been reworked accordingly, since the earlier claim that regulation lies on the path between all other domains no longer holds; the intervention asymmetry is now stated in terms of what each pathway carries, with social processes bearing on what a person can mean and regulatory processes on what a person can sustain. Section 8.2 revised to match. Section 6 also states a new prediction: individuals in comparable regulatory states but different discursive environments should construct systematically different narratives from the same bodily experience. Minor corrections to Sections 2.2 and 3.1. Revisions prompted by review correspondence with David Nylund, now acknowledged in the front matter.