Sherab Dorje wrote: "Master Gotama, what is the reason, what is the condition, why inferiority and superiority are met with among human beings, among mankind? For one meets with short-lived and long-lived people, sick and healthy people, ugly and beautiful people, insignificant and influential people, poor and rich people, low-born and high-born people, stupid and wise people. What is the reason, what is the condition, why superiority and inferiority are met with among human beings, among mankind?"
3. "Student, beings are owners of kammas, heirs of kammas, they have kammas as their progenitor, kammas as their kin, kammas as their homing-place. It is kammas that differentiate beings according to inferiority and superiority."
And how do you define all of those things?
Either by arbitrary concerns based on appearances
or as aspects of mind.
What makes a person rich is not how much money they possess
but their own mental experience of richness or poverty.
This is evident in the fact that a person with a lot of money
can go through life feeling as though they never have enoughto make them happy
while a person with very little money, a monk perhaps,
can go through life experiencing that they always have enough,
or more than enough to be happy
and freely generous as well.
People who spend their lives obsessed with their physical appearance,
starving themselves, yet they always see a fat person in the mirror
always experiences ugliness even though in the eyes of others they might be quite beautiful.
That is suffering.
If the Buddha was only concerned with the outward appearances of things
which have no intrinsic reality, but are only composites,
subject to constant arising and decay,
then being born of high or low status, or with a certain physical attribute of the body
or some relative degree of what we call (and are rapidly redefining) as "intelligence"
...all that would matter.
But that isn't what the Buddha's teachings are concerned with.
What the Buddha's teachings focus on is the perfect cessation of suffering,
and suffering is the activity of the mind. Not of the eye or ear or foot.
As has been pointed out, you can't just pick a thing at random
and say it is the result of good or bad actions
because that is only a reflection of your own personal bias for or against that condition.
and has nothing to do with the mind of the person experiencing that condition.
So, you might look at everyone who has less money than you and say
"that is because of their negative karma"
and look at everyone who has more money than you and say
'that is because of their positive karma"
but which of those people is happy, and which is unhappy?
And, specifically, what action in a past life causes arthritis in this life?
If I kill a mouse, will i be reborn as a mouse?
if that's the case, then I should kill a buddha.
Unless you can pinpoint exact causes and effects
such speculation is pointless.
We can say, "yes, all of your present conditions are the result of actions in the past
but it means nothing. It has no bearing on the future
so don't concern yourself with it."