Don’t you mean “speaking as an identical twi”? Because there’s only one of you.
You can also compare the physiological changes of any non-twin - its just now, they have atleast 1 example of ‘before and after’ with a ‘before’ still available.
I don’t think you’re wrong, but I don’t think there’s anything wrong with “twins study.” I’m trying to figure out similar instances that are more analogous. Like “couple therapy” and “couples therapy” (though that can also be “couples’ therapy.”) The latter sounds a bit more correct to me than the former. Looking at Google ngram viewer, the latter is much more common, though sometimes rendered as a possessive (i.e. “couples’ therapy” or “couple’s therapy.”) When I put the quote marks on both phrases (which I hope excludes the possessive usage), “couples therapy” is still more commonly used.
I’m thinking about why this may be. There’s something about treating “twin” separately and “twins” as a group to me that makes it sound to me like it’s not perfectly analogous with the dog-dogs example. Googling, the phrase clearly goes both ways. Here’s “Twins Research” from SRI International, an American non-profit research group. MSU has Twin Studies. NASA has Twins study. Wall Street Journal says twins study. Another WSJ article (you have to dig into the text) says “The political scientists say it’s not enough to see a pattern in a twin study or even to identify a suspect gene.”
That’s why I said it’s a separate issue, because that part of it is a little more nuanced and subject to a good bit of discussion, as opposed to the statement that “twin” is a plural already, or that it is a collective noun. It is neither.
You must’ve been absent for longer than that. Did you somehow miss all references to the Olsen Twins during the 1990s? Did you call Mary-Kate and Ashley the Olsen Twin?
Or the Spearmint Twins in the 1960s?
Or so many sitcoms in the 1980s where a character brags about “dating twins”? That is quite hard to believe.