It's complicated :-)

The problem is that there is considerable genetic component in "impulse control and self-discipline" and it also affects your (and your parents') socioeconomic class. And additional problem is that the effects of parenting style are asymmetric -- it's relatively easy to royally screw up a kid, but it's very hard to improve a kid beyond his/her genetic baseline. Yet another problem is that certain possible outcomes of studying this topic are politically incorrect and likely to lead to... undesirable career consequences for the researcher.