You are what your deep driving desire is.
The Bhadrayaka Upanishad is one of the older, "primary" (mukhya) Upanishads commented upon by Shankara. It is associated with the White Yajurveda and the Shatapatha Brahmana. It figures as number 10 in the Muktika canon of 108 Upanishads.
I'm male, say nothing
I'm male, single
I'm female, taken