Assume that after one dies, his separated soul goes to heaven. If sexual identity were not also spiritual, how could God or a heavenly inhabitant, upon looking at that soul, find out whether it was male or female? Or do you think that human souls are neuter?
Do you mistakenly think angels are also sexless?
Moreover, sexual identity is spiritual first and bodily second. If it were not, the transsexuals would not resort to monstrous measures to make their bodies look like those of the opposite sex.
Gender is not of course a mere subjective preference. But it may be an indelible spiritual identity.
Transsexuality is mind over matter taken to insane extremes. And the mind remains master even in this most favorable to matter contest.