This is a reference request, not a doctrine question. I recall seeing a quote from a Buddhist text or teacher roughly to this effect...
- To see your past karma, look at your present body (and environment).
- To see your future lives, look at your present mind.
The closest I can find now from a teacher or text is a quote from Philip Kapleau's Three Pillars of Zen...
Thus our present life and circumstances are the products of our past thoughts and actions, and in the same way our deeds in this life will fashion our future mode of existence.” (p. 408)
... which is close -- "life and circumstances" vs "body and environment" and "deeds" vs "mind"-- but not quite. If anybody can supply a pointer to the body/environment/mind version, I'd be grateful.