I am a firm believer in the powerful role of genetics in shaping children's personalities. In fact, if asked I would say that our personalities, intelligence, and skills are mostly determined by genetics. While research on this topic is still in its infancy, the more we learn, the more obvious genes' influence becomes. Modern parents probably ascribe far too much power to themselves in shaping their children's outcomes (whether for good or bad). This is not a popular point of view, especially in the circles I am familiar with, and even offends people (perhaps one reason why it attracts me, given that I enjoy being a contrarian).
However, I also believe strongly in the power of parenting to affect children's development and later lives. Childhood experiences seem to have a permanent and profound impact, in particular on social skills, empathy, morals/values and emotional and psychological adjustment. Everyone I have personally known with psychological or addiction problems has them largely due to the parenting which they received (though of course the role of genetics in increasing one's likelihood of developing these problems is also important). In addition, the severity of these problems varied almost entirely based on the quality of the parenting (with people with relatively functional parents being able to face and surmount their problems, while people with progressively worse parents were increasingly unable to do so).
Although it's non-PC to say this, I think the most important influence on a child's successful development is its relationship with its mother. Everyone I have ever known who was left motherless early struggles with anxiety and depression in varying degrees, carrying a permanent psychological scar. Several studies suggest that losing one's mother actually kills children. Although a neglectful or insensitive mother is better than no mother, the resulting ill effects are just as real, predisposing children to depression, anxiety, behavior problems, poor social skills, and a lack of empathy (aka not being a nice person). So as a mother, I feel my responsibility is a heavy one.
So then the question is, how can I be a good mother? Unfortunately, after reading many parenting and child development books, it's clear to me that there is no real consensus on this question. CIO, attachment parenting, strict sleep schedules, daycare, timeouts, star charts, and so on: there are many arguments for and against, but no real answers. Some things seem better (breastfeeding, for example) and some things worse (spanking, for example), but for the most part nobody really knows. Considering the central importance of parenting to our species, I find this surprising and frustrating.
What does seem clear is the importance of a mother being sensitive (to the child's feelings and needs), warm and accepting (regardless of the child's talents, abilities or defects), and responsive (open to a relationship in which each person influences the other). I would prefer that these qualities were a little less vague, but I suppose that is part of the responsive piece: each child is different, so a mother must be different too, even with each child that she has.
I only hope that I can succeed at being sensitive, warm, and responsive enough to give little R the necessary internal resources to get along in our challenging world.