Quote Originally Posted by ElaineB View Post
It has been proven beyond doubt that brain structure is partly determined by heredity and not everyone has the same basic brain.
They don't? Humanity has different basic brains? That would make them a different species if true.


Twins separated at birth tend to have the same personality traits.
I presume you mean identical twins, yes genetic clones are likely than not to produce similar personalities but this is not always the case.

My father and I (and most of the men in that side of my family) have very similar personalities but he did not raise me.
Sorry circumstantial. I have a similar personality to tens of millions of people in this world who have no connection to me. Finding similarities between family members runs into the same issues as people believing horoscopes - we find the answers we want to find.

So it is quite conceivable that there are such inborn differences between male and female brains
Conceivable yes but based on our knowledge of the types of code found in our genes then not likely because gender in the way that transgendered understand it and use it is a social contruct that our genes are blind to.



Abnormal is only meaningful if there is a norm.
Correct but there are norms. Any genetic variation that produces a profound disadvantage is not dispersed in the human gene pool because these people do not procreate due to natural selection pressures. However genetic variations may bypass natural selection if they are not apparent because complications either occur later in life or due to specific circumstances such as changes to our bio-chemistry. As a result some disadvantageous genetic variations bypass the evolutionary forces which is now a problem for us because most people can now expect to live a long life which is an unnatural state of affairs.


Evolution is not progress. It is just an extension of adaptation.
The creation of the human mind is not progress? Most evolutionary changes are indeed adaptations to a changing environment but some of these changes do in fact progress the animal to a more advantageous position. Indeed the more progressive the adaptations the more secure the creature will be in its survival since it will be able to cope with severe shocks that will kill off most species. So once a progressive adaption is found evolution will naturally build upon it.

The uniqueness of humanity is that a large learning self-aware brain is a gigantic progress.

So it really is just not true that all genes are still in our coding because they were advantageous, and it does not follow that a TG gene (if such exists) would have to provide some advantage somewhere.
But if the gene exists it is there because it was in fact used during our evolutionary past and was at the very least not disadvantageous or it would have been routed out by natural selection.

It is important while discussing theoretical issues to remember to remember what we are discussing. What we understand about gender excluding the sexual roles is based on a social construct which each society can define for itself. How can our genetic construction blueprint reflect a social construct. It would be like stating our genes influence what type of music we like or what type of art we enjoy.


What biological or social advantage does it provide anybody to have earlobes? None that I can see, yet they exist anyway in some people and not others.
Precisely because it had no disadvantages it was never a consideration in the forces of natural selection, it exists simply because people found it attractive enough not to discriminate against it.