Karma is the law of moral causation. The theory of Karma is a fundamental doctrine in Buddhism. This belief was prevalent in India before the advent of the Buddha. Nevertheless, it was the Buddha who explained and formulated this doctrine in the complete form in which we have it today.
What is the cause of the inequality that exists among mankind? Why should one person be brought up in the lap of luxury, endowed with fine mental, moral and physical qualities, and another in absolute poverty, steeped in misery? Why should one person be a mental prodigy, and another an idiot? Why should one person be born with saintly characteristics and another with criminal tendencies? Why should some be linguistic, artistic, mathematically inclined, or musical from the very cradle? Why should others be congenitally blind, deaf, or deformed? Why should some be blessed, and others cursed from their births?Either this inequality of mankind has a cause, or it is purely accidental. No sensible person would think of attributing this unevenness, this inequality, and this diversity to blind chance or pure accident.
In this world nothing happens to a person that he does not for some reason or other deserve. Usually, men of ordinary intellect cannot comprehend the actual reason or reasons. The definite invisible cause or causes of the visible effect is not necessarily confined to the present life, they may be traced to a proximate or remote past birth.
According to Buddhism, this inequality is due not only to heredity, environment, "nature and nurture", but also to Karma. In other words, it is the result of our own past actions and our own present doings. We ourselves are responsible for our own happiness and misery. We create our own Heaven. We create our own Hell. We are the architects of our own fate.
Perplexed by the seemingly inexplicable, apparent disparity that existed among humanity, a young truth-seeker approached the Buddha and questioned him regarding this intricate problem of inequality:
"What is the cause, what is the reason, O Lord," questioned he, "that we find amongst mankind the short-lived and long-lived, the healthy and the diseased, the ugly and beautiful, those lacking influence and the powerful, the poor and the rich, the low-born and the high-born, and the ignorant and the wise?"
The Buddha’s reply was:
"All living beings have actions (Karma) as their own, their inheritance, their congenital cause, their kinsman, their refuge. It is Karma that differentiates beings into low and high states."
He then explained the cause of such differences in accordance with the law of cause and effect.
Certainly we are born with hereditary characteristics. At the same time we possess certain innate abilities that science cannot adequately account for. To our parents we are indebted for the gross sperm and ovum that form the nucleus of this so-called being. They remain dormant within each parent until this potential germinal compound is vitalised by the karmic energy needed for the production of the foetus.
Karma is therefore the indispensable conceptive cause of this being.
The accumulated karmic tendencies, inherited in the course of previous lives, at times play a far greater role than the hereditary parental cells and genes in the formation of both physical and mental characteristics.