This post is not a scientific explanation, but simply a response to some of the comments on my previous post about intersex. So for totally clarity:
Intersex is a physical medical condition. There are always clear physical testable signs. For example, deformed genitalia or the presence of both male and female reproductive organs.
Transsexualism is NOT an intersex condition. There are no physical signs of Transsexualism, it is a psychological condition. So someone is a Transsexual because they say they are a Transsexual. There are no physical signs for Transsexualism.
Anyone claiming Transsexualism is an intersex condition is either misguided or lying.