Data is Beautiful

Christianity

My guess is the billions that the US has spent to export evangelical bigotry in Africa.

Disclaimer: I'm not an expert, but more familiar than most westerners.

Nigeria has a particularly rough history of religious extremism and totalitarianism. Even a lot of the indigenous beliefs were particularly intolerant (although this varied a lot, as Nigeria is an extremely diverse nation). These beliefs are rare nowadays, but still influence the culture and superstition. Adding to this, you have the influence of two abrahamic religions - in the north is a significant Islamic population, and in the south, Christianity largely imported (and enforced) by the British. I can't speak for the Islamic beleifs, but as was the case in many other places, the Christian beliefs imported and enforced were generally more conservative and extreme, and less allowed to change.

As well as this, the brutality of both regional warlords, colonization, then multiple different military dictatorships that followed, and now an ineffective government where terrorism and organized crime are common, lead many people to become more religious. Even now with a (relatively) stable and calm government, churchs and mosks are still one of the only sources for social assistance and security in communities. At the same time, the central positon of these churches leads to them being very corrupt and greedy, often being run more like a cult than a church as we tend to think of one. At the same time, in the modern world, this greed mean they also take in a lot of money from influential "Christian" organizations, for example, a lot of very rich, very political Anerican mega-churches, and will happily bend their teachings to appease wealthy donors.

All of this has led to Nigeria being effectively a perfect storm for homophobia and religious discrimination despite being (relatively) free.

Given the statistics, even gays are homophobes there

Not a lot of gay orgies at least

It's likely religion doing its thing again

Unfortunately every country has their low-water-mark percentage of irredeemable bigots. Thankfully most of them tend to live out in the middle of nowhere, away from civilised people.

it's common sense that homosexuality is acceptable when it's between two hot women /s

My guess: Larger % of people living in city centers vs rural areas. A quick glance at population data over time seems to back that up, but you know what they say about correlation.

It's a really good question, I'm from Argentina and I don't have a solid answer. Like someone else said the colonization and history is likely to be part of the reason, but I would like to remark that Argentina has a lot more influence from Italy, Spain, Germany and France, and also Jewish ( iirc Buenos Aires used to be the city with the largest jewish population after New York in the 90's). It's a very different cultural melting pot compared to any other country in South America.

Maybe has something to do with the type of colonisation in each country. Argentina had its first university in 1613, while Brazil had its first in 1808. Brazil as a colonial project kept its extractivist nature for a lot longer.

The data appears to be very incomplete for Africa. Hit the play button, then scroll through dates.

https://ourworldindata.org/grapher/share-of-people-who-think-homosexuality-is-never-justified?time=1984..latest&country=PAK%7ERUS%7EUSA%7EAUS