1. It's not Critical Gender Theory, though Critical Gender Theory uses broadly similar definitions for the subset of those things which it thinks are worthy of discussion, it's just the fairly common language to distinguish the innate physical (sex broadly, reproductive function for the particular subset you raised), internal self image (gender identity), externally ascribed status (gender), and behavior (gender presentation), and neutral as to material as opposed to conceptual relationships. CGT is opinionated about the material relationships, holding (as I understand it, but CGT isn't something I've more than casually encountered) that gender presentation is socially learned behavior produced by social gender ideas and other aspects of personal social context, gender identity (which CGT doesn’t, IIRC, talk much about directly, but recognizes insofar as it recognizes that people have a social identity related to the social construct of gender) as a product of gender presentation and social gender stereotypes (reversing a common progressive view that gender identity is a fundamental, immutable or nearly so, aspect of identity amd that gender presentation is an expression of identity, to which social gender images may play a part.) 2. It (my post, not Critical Gender Theory) is not supposed to be scientific; it's pretty much all definition of terms, which precedes the ability to even discuss observations of facts, which in turn precedes the ability to discuss hypothesized generalizations from observed facts and empirical tests of those generalizations.