FlemishHorse
The modern term is person with a DSD. "Intersex" is rude and othering. Everyone with a DSD is either male or female. Some DSDs only affect males, others only affect females.
Caster Semenya has 46 XY, 5-ARD. Caster is male. The 46, XY bit just means male. The 5-ard bit refers to alpha-reductase deficiency, which prevents the synthesis of testosterone into DHT, which is the hormone that promotes the development of external male sex organs.
5-ard is heritable. If Caster had had a twin sister, she would not have been affected because the development of a penis is not part of female sexual development.
Men with this condition usually look unambiguously male, though they lack facial hair. They have internal testes which produce male levels of testosterone. They go through normal male puberty and often the penis develops a little more at that stage. They are fact normal males apart from the appearance of their external genitals.
CAIS/PAIS are conditions in which males do not have the receptors to respond to the signals of the various androgens they produce. CAIS stands for complete androgen insensitivity syndrome and PAIS stands for partial androgen insensitivity syndrome. CAIS males in effect never go through male puberty. They are taller than average for men because the testosterone surge at puberty would normally act to limit growth. They have no female sex organs except a sort of proto-vagina, a short blind pocket. Hormones and enzymes for sex development work both by triggering sexual development and suppressing opposite sex development. For example, the instructions to make a penis are also the instructions to NOT make a vagina. That is why a DSD affecting the penis can result in a blind pocket. Breast development would be similar to a female because not counteracted by the effect of androgens. If you met a CAIS male, you would think you were meeting a woman.
PAIS males can respond to and utilise testosterone and other androgens to some degree and may experience changes in puberty.
Women can pass on the gene for AIS but never have the condition themselves, obviously.
The whole area of research is fascinating, but you always have to remember you are talking about real people with real health problems, most of which are not to do with having ambiguous-looking external genitalia.
I'm still quite curious about what you were getting at with the sense of femaleness theory. How do you envisage it developing?