Controversy In Thai Buddhism

I think that some karmic events are logical. Revenge, as you mention, is a good example.

But on the far other end of the spectrum, just for example, a karmic event that occurs in separate lives (for example, a person is handicapped in this life because it is bad karma from a previous life).

Assume that reincarnation is real ...

There are heaps of babies being born each day. Why does someone come back in a inferior body. What we have been thought in Thai Buddhism is that we choose which womb we're going to be born in. So logic would say to me that it's the matter of bad choice + all other factors. Let's assume there are souls, then there should be some interaction between them. Revenge may still be a factor for a soul to make a bad choice. Makes a lot of sense to me. Unless someone ends the grudges, it will keep going on & on.