In truth, nobody can change either race or sex. In the ultimate Darwinian sense, transsexuals and transracials are as real as witches.Read the whole thing there.
Philosophers, at least since Descartes’ “I think, therefore I am,” have tried to figure out how to ground their perceptions of the world in something assuredly factual. But here’s what we can say with some confidence about the human race: At this point in time, every mortal human has had one biological father and one biological mother; one biological paternal grandfather, one biological paternal grandmother, one biological maternal grandfather, and one biological maternal grandmother; and so forth. In the future, humans might be cloned and thus have only one biological parent, or might be genetically engineered to have three biological parents. Anything could happen. But so far it hasn’t.
The most rigorous definition of a racial group is a partly inbred extended family. Race is about who your ancestors are on your biological family tree. Nothing Rachel Dolezal can do can change her genetic lineage.
(By the way, the U.S. Census Bureau has typically drawn a distinction between race, which it describes as biological, and ethnicity, which it calls cultural. A useful way to think of ethnicity is as those traits such as language, religion, cuisine, names, customs, and so forth that are typically passed down within biological families, but don’t, technically, have to be.)
Moreover, we can rigorously define anyone who has fathered a child in anybody’s family tree as a man and anyone who has given birth to a child in anybody’s family tree as a woman. No ancestor anybody has had has done both. So far, the human species doesn’t actually work as assumed in Robert A. Heinlein’s 1959 sci-fi story “—All You Zombies—,” in which a sex-change operation and a time machine allow the narrator to be his/her own father/mother and son/daughter. Maybe someday Heinlein’s story will come true, but it hasn’t yet.