I'd skimmed a paper from a couple of years ago, How Universal Is the Big Five? Testing the Five-Factor Model of Personality Variation Among Forager–Farmers in the Bolivian Amazon. Abstract:

The five-factor model (FFM) of personality variation has been replicated across a range of human societies, suggesting the FFM is a human universal. However, most studies of the FFM have been restricted to literate, urban populations, which are uncharacteristic of the majority of human evolutionary history. We present the first test of the FFM in a largely illiterate, indigenous society. Tsimane forager-horticulturalist men and women of Bolivia (n = 632) completed a translation of the 44-item Big Five Inventory (Benet-Martínez & John, 1998), a widely used metric of the FFM. We failed to find robust support for the FFM, based on tests of (a) internal consistency of items expected to segregate into the Big Five factors, (b) response stability of the Big Five, (c) external validity of the Big Five with respect to observed behavior, (d) factor structure according to exploratory and confirmatory factor analysis, and (e) similarity with a U.S. target structure based on Procrustes rotation analysis. Replication of the FFM was not improved in a separate sample of Tsimane adults (n = 430), who evaluated their spouses on the Big Five Inventory. Removal of reverse-scored items that may have elicited response biases produced factors suggestive of Extraversion, Agreeableness, and Conscientiousness, but fit to the FFM remained poor. Response styles may covary with exposure to education, but we found no better fit to the FFM among Tsimane who speak Spanish or have attended school. We argue that Tsimane personality variation displays 2 principal factors that may reflect socioecological characteristics common to small-scale societies. We offer evolutionary perspectives on why the structure of personality variation may not be invariant across human societies.

I'm no expert on this, but I refer you to Yvain's series on The Last Superstition by Ed Feser: one, two, three, four. As Yvain quotes Feser:

A squirrel will be a better squirrel the more perfectly it participates or instantiates the form of a squirrel. A squirrel who likes to scamper up trees and gather nuts for the winter (or whatever) is going to be a more perfect approximation of the squirrel essence than one which, through habituation or genetic defect, prefers to eat toothpaste spread on Ritz crackers and to lay out "spread eagled" on the freeway. This entails a standard of goodness, and a perfectly objective one. It is not a matter of opinion whether the carefully drawn triangle is a better triangle than the hastily drawn one, nor a matter of opinion whether the toothpaste-eating squirrel is deficient as a squirrel. If a squirrel could be conditioned to eat nothing but toothpaste, it wouldn't follow that this is good for him.

I think the idea is that a homosexual human is a toothpaste-eating squirrel - the instantiation has deviated from its ideal form. And unlike squirrels, humans can reason and choose whether to act in conformity with our supposed nature.

If you assume some unsubstantiated premises, I guess this makes sense. And that's why people are talking past each other when they argue about whether homosexuality is natural. The theist claims homosexuality isn't natural, taking "natural" to mean "conforming to the ideal form". The liberal points to homosexuality in animals, taking natural to mean "appearing in nature".

(I may have horribly distorted this - I haven't read the book.)

Edit: Here's a theist talking about the book, in case you want an explanation from a believer.