Is parenting related to adult behaviors?

This week for class I read an article about how early child-rearing techniques influenced later, adult personalities. This study used surveys from a 1951 study about mothering techniques and later contacted their children who were now about 31 years old. The results showed a correlation between mothers with strict toilet training and scheduling of feeding and children with high needs of achievement. Mothers who were permissive about sex and aggression had children who were high in needs of power.

This article made me think about how much early childhood experiences really have on our behaviors and if it does affect our different needs in adulthood. Is it even possible to study this connection or are there too many intervening variables between childhood and adulthood? In another class I am taking this semester (Psychological Anthropology) we discussed the differences in child-rearing techniques between American mothers and Gusii mothers. American mothers spent more time looking at and talking to their children while Gusii mothers spent more time holding their child. These parenting styles represented what was important in the different societies; Americans value independence and individualism while Gusii value collectivism and society. So, were the adult behaviors created by the parenting techniques in their childhood? And why does this correlation even matter?

Personally, I have some trouble making this connection. I think it may be because I need more concrete proof of the correlation between the two variables rather than just observations. And even if there was a cause and effect relationship, I don't think it matters that much. So what if a certain parenting technique creates an adult with a high need of achievement, is it really that important that people will either want to avoid that behavior or encourage it? What does everybody else think about this correlation?

Articles:

McClelland, D. C., & Pilon, D. A. (1983). Sources of adult motives in patterns of parent behavior in early childhood.

Levine, Robert A. (1999) Infant environments in psychoanalysis: A cross-cultural view.