Nature and all her systems crave equilibrium. That is true for human beings as well.
We may be born with the deficit of a certain quality – intelligence , looks, etc. The world around us makes us abundantly aware of our shortcomings. Hence we tend to desire those things that we lack.
Our constant hankering for those qualities makes us desire them tremendously. Therefore , in our subsequent life or lives, we are usually granted those things that we hankered for intensely in our past lives. This of course holds true when we have done enough good in the past life so as not too slip down the evolutionary ladder.
The same logic holds true for a situation where one of us is emdowed with a surfeit of one or more qualities. Nature tends to equalise things. Therefore , due to some reason or another , arrogance , vanity and propensity towards sense enjoyment and evil, we do deeds with negative karma and end up losing those qualities in our subsequent life and lives.