http://www.newsweek.com/id/134920

In this article, researhers from the University of Maryland, Duke, and Johns Hopkins used game theory to predict levels of parental discipline.  They found that parents really do become less strict with younger children and the effects show.  Parents are less likely to financially support rebellious older children if there are younger children at home, and having one more younger sibling causes a teen’s high school drop-out rate to go down about 3%.  Younger children, with lessened parental discipline are more likely to engage in risky behaviors like unpredicted sex, smoking, and drinking. The article suggests that the reason parents are stricter with older children is that they want to prevent older children from setting a bad example for younger ones.  By the time younger children run into similar issues, parents respond with love instead of discipline, so younger children don’t need to fear severe consequences or rejection from parents.

The article’s main motivation for strict regulation with older children is that parents have to keep order in the house for the sake of the younger children.  Although this may be a part of the parent’s motivation, another factor could be the parent’s unfamiliarity with facing a particular issue.  If, for example, a parent discovers that the oldest child in the family has started smoking cigarettes, the parent, knowing how destructive the behavior is, will be very upset and concerned and may impose severe consequences on the child to try to stop the behavior.  If the attempts to stop the first child were unsucessful, the parent may reflect that their strict response was unsuccessful and only added tension to the relationship.  Then if a second child starts smoking, the parent will still be very upset and concerned, but may be less harsh with the second child to preserve the relationship. So, parental leniency with younger children may be caused by experiences in earlier “trials” as well as the absence of younger children at home that need a clear example.