Ken isn't necessarily wrong in my opinion, of course it all boils down to personal belief.
Like because social and twitter arguments are lame, its interesting to look at in detail.
Theres parts in the subcortical region of the brain that are responsible for things like memory, emotion but most importantly in this case hormone production.
Out of the journals and studies I've read on the neurobiology of transgenderism, the brains of transgender folk most commonly differ from cisgender individuals in this region in volume and surface area. Ken mentioned a recessive gender that acts as your "brain gender" which may actually be correct as the subcortical region and white matter structure tends to be more in line with their percieved gender rather than their "at birth"gender.
Theres also similar differences between the cis-woman and cis-mans brain in the cortical and subcortical regions in brain volume and other structures.
Its interesting tbh.