In the past several posts I’ve explored some aspects of the phenomenon of “Mormon horns.” In this post I’ll throw out some observations that didn’t fit in well elsewhere.
Moyle horses derive from horses owned by Mormons and have “horns.” I look forward to the day I meet a Mormon riding a Moyle horse, whereupon I hope to say, “You have horns. And the horse you rode in on!” 
A Contradiction of Sorts
I frequently encountered statements like, “they studied us as intently as if we had horns…” If horns represented real danger, people would run away rather than ogle (one presumes). Identity horns are, therefore, not just a mark of evil, but also of intrigue and interest. You put horns on them precisely so you can look at them. On the flip side, the TBWHH crowd also emphasizes the horns as a way to get people to look. They are a boundary marker, but not a privacy fence. 
To me, the most striking realization in researching was how non-unique Mormon horns were. However, I think there remains room for a Mormon aspect. Thus sayeth Google: Some phrases about horns appear significantly more often when applied to Mormons than when applied to Protestants or Catholics. 
|Number of Google Hits for Selected, Exact Phrases|
|1. “do ___s have horns”||0||0||28||18|
|2. “___’s horns”||0||0||4||33|
|3. “[adj form of ___ ] horns”||20||13||69||870|
|4. “___s had horns”||3||20||60||60,000|
|5. “___s have horns”||5||25||32,000||80,000|
Some Conjectures on TBWHH Propagation
- A Them makes figurative remark about Us horns
- Literalist Us takes it literally / physically and then
- Tells other Us-es people about it
- Urban legendry does its thing. Then, the key points:
- Us-es—especially missionaries—go into the world and “sample” a large number of reactions to the Us. The topic somehow comes up. 
- Confirmation bias kicks in: small actions/statements by the Them that a third observer would not call confirmation get called confirmation by the Us. 
- Us returns and reports. Lather, rinse, repeat. Contact with eyes may cause irritation.
Thus… at least in one scenario, what is essentially a verbal syncopation gets attributed as a belief.
Potential Future Research
- Change over time. Did all these horns move with other events? Cresting anti-Semitism in the 1920s and 30s? the “Catholic Moment” in the 60s? the Manifesto in 1890?
- Change in geography. Anecdotally, the Mormon-horn stories I hear are shifting from, “Growing up in the Bible Belt…” to, “On mission in Guyana…”
- Differences in social architecture. If Mormon horns are like other horns, we should explain how different groups end up with a similar phenomenon. I conjecture Mormonism might be able to sustain a more urban-like urban legend than other groups because of its greater integration, relatively small population, and persistent peculiarity. 
Mormon Horns 1, 2, 3, 4, 5, 6, 7. These horn posts continue earlier efforts analyzing ways of describing Mormons or using Mormons to describe something else. These include: India, Cows, Bluebeard, Lice, Crickets,Flies, Happy Valley, and sundry other beasts.
 Bonnie L Hendricks and Anthony A Dent, International Encyclopedia of Horse Breeds (Norman: University of Oklahoma Press, 2007), 296-298; Jessie Haas, Hoofprints: Horse Poems (New York: HarperCollins, 2004).
 I think research on Mormon villains and sexuality in dime-novels resonates here.
 Queries run 2009 Sep 02, 0800 CDT. What this data indicates other than that “something” is happening remains unclear. The hits might mostly be from Mormon anti-horn apologetics.
 I assume that in the sample are a few people with some combination of poor verbal reasoning skills, non-inquisitive minds, slow thought processes, general gullibility, deference to authority, and so on.
 Potential psuedo-confirmations might include: getting flustered while trying to process the cognitive dissonance of a human with horns; actually looking/feeling when the Us offers to verify their hornlessness; saying something credulous-sounding “I heard Us-es have horns. They don’t, do they?”
 Mormons who keep minimum standards blend in pretty well—but not like most Catholics, Protestants, or (non-orthodox) Jews keeping their minimum standards.