Finished reading "The Corrections". I have some questions: To what extent does our past/upbringing influence our present? Do things happen for a reason?

Recently finished reading "The Corrections" by Johnathan Franzen.

Anyway, in that novel, a lot of the present behaviors (and problems) of the characters can be explained in terms of their upbringing and early experiences and also in terms of reactions to the way of life of their parents. It appears that, to a large extent, things happen for a reason.

In particular, all of the Lambert children seem to be, in their own ways, trying to rebel against or react to the values of their parents. Chip goes all the ways against the values of practicality and productive work by choosing a career in (not so well paying) humanities, and even there sabotaging his own success. Gary tries hard in his own marriage not to be like his father, but only partially succeeds. Denise overreacts against sexual repression and female submissiveness of her mother by becoming a tomboy and being rather promiscuous and wild and also distant in her relationships.

In short it appears that lots of things happen for a reason and can be explained in terms of the distant past.

I am wondering to what extent is that true in real life? Or is fiction overemphasizing such things because it would make for a bad story if life was depicted as more random?

To what extent does our past/upbringing influence our present? Do things happen for a reason?