If your company is an ISV and your personal responsibilities include development or marketing, you need to build your products faster and compete more effectively in your vertical markets.
Since the 1970s, however, studies devoted to understanding the personality characteristics of only children have debunked that idea. I, for one, was happy without siblings.
The studies on gender income differentials which are based on individual income data in the literature decompose income differentials and measure the discriminatory.
Ultimately, whether an advertisement makes a person feel better about him or herself depends on the individual and how they perceive themselves as compared to the particular advertisement in question.