>>1305247
Most people like to attribute the magic resistance of Bretons to their mer ancestors, but that simply can't be. As their mer ancestors are the Aldmer, who are most closely related to Altmer. The Altmer having a weakness to most magics.
So one might surmise that this racial trait must come from selective pressure of that the Bretons encountered in their enviroment. High Rock isn't any more magical than the rest of Tamriel, so it must be something to do with their culture.
Bretons have a very cutthroat culture were people try to obtain as much power and wealth that they can. But that bit of their culture isn't what seems to have caused this little quirk. You see many Bretons are raised studying magic, conjuration being their most studied school. So much so that most conjurers you find around Tamriel are Bretons. Now you might be wondering why this is important, but you'll understand after considering such: flame atronachs.
Imagine if you will that you're a young Breton boy just coming of age, your southern member has been acting funny recently. Then one day your magic tutor teaches you a new spell, summon flame atronach. Once summoned you seemed to become bewitched, the deadra's long elegant legs, her wide childrearing hips, and shapely chest steal all your attention. Feeling an odd sensation underneath your apprentice robes, you rush to your study chamber. What comes next is a long study session involving both conjuration and restoration spells.
Those who had a lacking resistance though, wouldn't be able to handle this endeavor, leading to them being unable to procreate. Thus only the most magically resilient Bretons sowed the seeds of the future of High Rock.