We tend to forget it, and only get reminded when we feel sore or when something’s wrong, but of course we are bodily beings. Even with all the complications that have come to surround gender, let alone sexual orientation, it would appear to be a basic fact of life that we are also (predominantly) either male or female.
As far as facts of life go, that should be obvious. What we make of such biological facts, however, can be very different, and have great influence in intercultural interaction.
Just take the usual encounter between Chinese and others.