Motivations, I listed the differing motivations of twenty four different Poul Anderson characters.
In Motivations II, I proposed that each intelligent being is both a unique combination of genes and a unique organism-environment interaction, the point being that the characters' motivations differ because they are determined by uniquely different sets of genes followed by unique interactions. Further, which gene-bearing sperm and egg meet in the first place is a matter of luck.
For an earlier Motivations II that I had forgotten, see here.
See also Changing Motivations and Basic Motivations.
In Luck, I quoted the view that chance or luck alone determines those developments within the brain which in turn make the difference between genius, average ability or ineptitude, e.g., in mathematics. No one can exercise conscious control over processes inside his own brain. On the contrary, some such processes must already have occurred before there exists an entity describable as a person capable of making conscious decisions or choices.
Our most basic motivations arise from a chance meeting between a sperm and an egg followed by a unique series of interactions between our organism and its natural and social environments, accompanied by chance events inside our brains. And all of this finally explains why Adzel in the Technic History wants enlightenment whereas the Neldorians in the Time Patrol timeline want luxurious living.