Here's a question I was asked earlier today, along with my first response, which I will post publicly as I am sure others can offer more complete thoughts than these:
"Do you know of any material on how Epicurus viewed differences from the start of life that are out of our control? For example, a baby being born into a rich family vs. a poor family and having more opportunities, or being born in adverse racial or ethnic or religious or other circumstances? Are these initial differences determined by Nature? I think not because that would imply some divine intervention?"
That's a good question and at first glance I am not aware of anything "completely" on point but I would point to several things that I think would lead to the answer pretty clearly.
As stated in the letter to Menoeceus and in other fragments Epicurus was against the idea that there is any "necessity" in human affairs, or that the gods intervene to produce their desired results. Therefore I think he would say that yes, there are natural inequalities of circumstances as a result of "accidents" of birth, but no, as you indicate, these circumstances are not determined by any predefined order by the gods or any kind of intentional fate, not directly nor by using "nature" as their tool.
Plus, we know from Lucretius that souls do not wait in line or choosing lots waiting to be born into particular bodies.
Another important thing is that we also know from Lucretius that through the use of human reason we can overcome many prejudices and circumstances. Lucretius indicates that there are natural limits to what can be accomplished through our own actions, and certainly people are born all the time with illnesses or disabilities which have no cure and hobble them for life or lead to early death.
But I think Epicurus would also say that even though many things are fully "accidental" as a result of the swerve of the atoms, there are also many things (and probably even true to say "most" things) that are not fully "accidental." "Most" things in the universe at large are in fact the purely mechanistic result of the atoms moving through the void and bouncing off each other or combining in completely natural ways. In most of those atomic combinations the swerve is not sufficient to break the deterministic "billiard-ball" chain of action and reaction. In support of that I have seen this reference to "law of regular succession" cited from the letter to Herodotus:
" Furthermore, the motions of the heavenly bodies and their turnings and eclipses and risings and settings, and kindred phenomena to these, must not be thought to be due to any being who controls and ordains or has ordained them and at the same time enjoys perfect bliss together with immortality (for trouble and care and anger and kindness are not consistent with a life of blessedness, but these things come to pass where there is weakness and fear and dependence on neighbors). Nor again must we believe that they, which are but fire agglomerated in a mass, possess blessedness, and voluntarily take upon themselves these movements. But we must preserve their full majestic significance in all expressions which we apply to such conceptions, in order that there may not arise out of them opinions contrary to this notion of majesty. Otherwise this very contradiction will cause the greatest disturbance in men’s souls. Therefore we must believe that it is due to the original inclusion of matter in such agglomerations during the birth-process of the world that this law of regular succession is also brought about."
That's the Bailey translation but there are others that I think make that underlined sentence even more clearly indicate that certain things that we might thing of as "inert" matter do in fact conduct their functions in billiard ball fashion, straight from as far back in time as when that particular part of the universe was originally formed.
I should add I think there's also a possible reference (Lucretius?) that the swerve might have been involved in the original formation of worlds in promoting the atoms becoming intertwined in the first place. But I am pretty sure I have also seen it argued persuasively that it isn't logically necessary that the swerve keep happening all the time in order for what we observe to be taking place to occur, so the main observation that leads to the deduction that the swerve exists is the free agency of higher animals.
This is a fascinating topic to me because it involves the issue of "how far does the swerve go in creating indeterminacy?" I think some people take the swerve way too far, and think it means that because atoms can swerve, anything can happen at any time. My view is that that would be an extreme position which cannot possibly be what Epicurus meant. My view comes from one of my favorite Epicurean articles of all time, which is called "Chance and Natural Law in Epicureanism" by A.A. Long. It can be found here: Article Added: A A Long's "Chance and Natural Law in Epicureanism"
I highly recommend that article to anyone who is interested in issues involving determinism or the swerve. The article covers a lot of ground, but the main takeaway I remember from it is that Long concludes from the texts that Epicurus held that the effect of the swerve is very limited: the swerve only "breaks through" to create visible results in our world only in a limited number of circumstances, primarily circumstances involving indeterminacy which we can see for ourselves, like the "free will" of higher animals to make their own decisions. Long argues that if the swerve was so pervasive that we could observe anything happening at any time, that observation (of all events being totally unpredictable) would undermine the entire foundation of atomism. If anything can happen at any time then atomism would be a totally untenable position and totally incapable of explaining the very many instances of the regular mechanistic workings of nature.
There's also an article by David Sedley which comes from another angle. Sedley suggests that the swerve really was not a physics position in the first place, but a deduction from human free will that was grafted back into the physics later, rather than emerging from as starting point in the physics. If I recall correctly, the Sedley article would be consistent with the Long article in limiting the indeterminacy caused by the swerve. In both arguments, even though the majority of things that happen in the universe are not "intended" by anyone or anything -- they do happen in a mechanistic and predictable fashion.
To summarize looking back at the original question: "Yes - determined by Nature" but "No - not as the result of any intentional or conscious plans by gods or nature."
If anyone else has any comments on this question please add them!