We need to recognise that gender is socially constructed. Politics is leached from this argument. It ignores the fact that commitment to feminism is not in our genes. Being born a woman does not guarantee support for women's liberation. Meanwhile, transgendered women, many of whom politically support the aims of the women's movement, who argue that existing gender relations are oppressive and who experience oppression both as women and transgendered women, are excluded.
Biological determinism is deeply fatalistic.
It means that women's liberation will always be unattainable while men exist. Arguing that specific socialised conditioning is fixed and, hence, unchangeable, faces exactly the same problem. This denies the fact that many transgender people realise from an early age that they do not fit the gender role dictated to them by society. This completely individualises transgenderism, blaming the victims of oppressive gender stereotyping rather than the system which creates it. The argument also implies that there is a great degree of choice involved, when transgender people are often aware of their true identify from a young age, and merely seek to change their body or their appearance to fit who they are.