Why do karmic reactions not come in this life itself?

Different seeds fructify after different time durations. Grains harvest after two or three months, some fruit seeds produce fruits after twenty years and some seeds may even take hundred years to fructify. Every action that we do is like a seed sown. The seed will fructify and we cannot escape the result. One may say, “I don’t like this fruit, I don’t want it.” But one will be forced to eat the fruit, even if it is thorny. The reactions will come, but different types of karma seeds (actions) have different time durations after which they fructify.

Why do different actions give reactions after different time durations? To understand this, let’s probe deeper into the mechanism of karma, as is illustrated through an incident from the Mahabharata.

After the bloody Kurukshetra war, Dhritrarashtra asked Krishna, “I had hundred sons and all of them were killed in the war. Why? Krishna replied, “Fifty lifetimes ago, you were a hunter. While hunting, you tried to shoot a male bird, but it flew away. In anger, you ruthlessly slaughtered the hundred baby birds that were there in the nest. The father-bird had to watch in helpless agony. Because you caused that father-bird the pain of seeing the death of his hundreds sons, you too had to bear the pain of your hundred sons dying.

Dhritarastra said, “Ok, but why did I have to wait for fifty lifetimes?” Krishna answered, “You were accumulating punya (pious credits) during the last fifty lifetimes to get a hundred sons because that requires a lot of punya. Then you got the reaction for the papa (sin) that you have done fifty lifetimes ago.”

Lord Krishna says in the Bhagavad-gita (4.17)

karmano hy api boddhavyam
boddhavyam ca vikarm an ah
akarm an as ca boddhavyam
gahanä karmaëo gatih

“The intricacies of action are very hard to understand. Therefore one should know properly what action is, what forbidden action is, and what inaction is.”

that the way in which action and reaction works is very complex. God knows best which reaction has to be given at what time in what condition. Therefore, some reaction may come in this lifetime, some in the next and some in a distant future lifetime.