Nature is infinitely variable. No two plants, animals, or humans are alike. The variations are usually incremental. A slight change in size, shape, or color resulting in a continuum of possibilities.
Give this, it’s no surprise that non-binary or non-conforming gender identity is not uncommon. In fact, it’s been a part of the human experience for as long as we have records. Hijra in Mesopotamia, Mahu in Polynesia, Two-spirited people in Native American culture, Hijras in India, Muxes of Oaxaca, Kathoeys in Thailand, Warias in Indonesia.
There have always been those who are unwilling to accept individuals whose gender identity doesn’t match their sex, and today there are efforts to legislate conformance to biological sex at birth or to discriminate against those who won’t.
This shirt is an acknowledgement of the difference between sex and gender and acceptance of individuals that express it.