I’m a Caucasian woman married to an African-American man. Shortly after we married, I discovered that I couldn’t conceive my own biological children. We opted to ‘‘adopt’’ two embryos. (Couples who have successfully undergone in-vitro fertilization and don’t wish to have more children can donate remaining embryos to other couples.) I was soon pregnant and gave birth to twins. Based on the records of the fertility clinic, we know that our children are genetically mixed Hispanic and Caucasian. I am not comfortable being open about the origin of my children, except with family and close friends, until they are old enough for me to explain it to them. However, several times in the last three years, I’ve been asked about their race, most recently on a pre-K school application form. On this form, there is no option of ‘‘mixed race’’ or ‘‘other.’’ Therefore, I identified my children as black. Was this the right choice? Name Withheld, Chicago

Ethics generally commends telling the truth. But in a situation in which our ordinary ways of thinking are at odds with reality, there can be no easy truth to be had. When it comes to race, confusion is the most intellectually defensible position. Let’s try to sow some. If your children were your biological children, many people in our society would say that they were African-American, because we have a tradition, going back before emancipation, of treating people with one black parent as black . . . or Negro or colored or whatever the favored term was at various times in American history. That’s the ‘‘one-drop rule,’’ so called because consistent application of it would mean that anyone with any African ancestry at all was black. (Of course, unbeknown to those who started this system, we all have African ancestry in the long run, which shows how much our thinking is shaped by our lack of knowledge.)

As it happens, millions of Americans are black according to the one-drop rule but don’t have any of the features that people associate with African ancestry. Lots of them ‘‘pass’’ for white. Many don’t, though. Walter White, the early-20th-century leader of the N.A.A.C.P., was able to travel the South investigating lynchings because, although his parents were ex-slaves, he ‘‘looked white.’’ His autobiography begins: ‘‘I am a Negro. My skin is white, my eyes are blue, my hair is blond. The traits of my race are nowhere visible upon me.’’ (In a bio­pic, he could have been played by, oh, Bryan Cranston.) ‘‘ ’Cause it’s swell to have a leader/That can pass for white,’’ wrote Langston Hughes, who with his ‘‘copper-brown skin and straight black hair’’ — his description — was himself taken for white during a trip to Africa and could have passed for Indian if he troubled himself to do so.

Race being socially constructed, things work differently in different places. In postwar Britain, the word ‘‘black’’ has been used for people of South Asian as well as African ancestry. In South Africa, ‘‘coloured’’ is still widely — though not officially — used as a racial category, referring to people of mixed Dutch and Asian or African descent, most of whom speak Afrikaans. In Brazil, less than 8 percent of the population identifies as ‘‘preto,’’ or black; over 40 percent of the population identifies as ‘‘pardo,’’ or brown, implying some mixture of African, indigenous and European ancestry. Almost all would, by tradition, count as black in the United States. Now, however, an increasing number of people in the United States reject the one-drop idea, and they might say that your biological children are mixed race. (Some might say they were not of any race except the human race.)