• What’s the debate? •
[2½ MIN READ]
One of our ACF guys has a twin sister. This means sis Jada and bro James are fraternal twins, dizygotic, i.e., ones that develop from 2 different eggs. Identical twins develop when a fertilized egg divides into 2, the halves containing the same genetic material. “Monozygotic” twins can be either male or female but not both.
This fact arose when we got to talking about twins after the last Arcadia Christian Fellowship club meeting. That’s when Vince asked James, “Are you and your sister identical?” And that’s when I barely stopped myself: “Vince, you idi…!”
Whether he actually realized his mistake or not, he broke into a self-conscious grin. I definitely realized my mistake and broke into my own self-conscious version: I had thoughtlessly and reflexively humiliated a student.
That’s when newcomer (and mutual friend of the twins) Laila insisted that mixed gender twins can be identical. As a biology major (and a same-gender fraternal twin), I explained the developmental process. I threw out the heady qualifier that they may be physiognomically (facially) identical, but not genetically.
When I got home, this became a personal research exercise. I was Arcadia’s Sciences Librarian for many years (iCandybyWangC.com). I know biology is complicated and wondered if I was somehow actually wrong. (Knowledge is a funny thing with few absolutes.) I started with a search on ‘male female identical twins’ (no punctuation).
Washington State Twin Registry says that in extremely rare cases, MZ twins can develop into a male/female twin pair (WSTwinRegistry.org). Its article is particularly useful for tackling this question because of its brevity, degree of detail, and readability.
The article references as sources a popular media article and 2 journal articles. Those and journal articles from additional searching present challenges to answering the question about physiognomic similarity. They all fail to specify if the rare instances they cite resulted in viable births. The sources certainly do not specify if the twins looked alike, which was the original point. So, mixed gender monozygotic twins are possible, but the phenomenon is so rare that there are no visual examples to prove identicalness of facial appearance.
Considering a different possibility, one MZ individual could undergo “gender confirming surgery” which results in a mixed gender pair with “identical” appearances. The account of one such pair was an Arcadia University incoming-student common-read book a bunch of years ago: Becoming Nicole (WashingtonPost.com).
To return to another concern, had I thoughtlessly and reflexively humiliated Vince? To the degree I did, it’s definitely not a recommended practice for ministry leaders.
Is he actually an idiot? Considering that he gave me permission to use his name to write this piece, it’s debatable.
As far as Jada and James, you can decide about the similarity of their appearance for yourself. Vince, what do you think?
As for my twin Bertram and me, you can also decide for yourself, but the jury delivered its verdict back to our youngest days that we are not identical.
FINE PRINT ¶ACFterward #15 ¶Text: Calvin Wang (Wäng), CC BY-NC-SA 4.0.
Calvin Wang serves Arcadia University‘s ACF (Arcadia Christian Fellowship) through CCO (Coalition for Christian Outreach. Respective websites.). He began serving as a staff member February 2026.
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