Lal,
I can only speak to my experience going through the background check, which was outsourced to Kroll, last year. I found them to be very thorough.
HR numbers are often requested so that those conducting background checks can verify dates of employment, positions, responsibilities, etc. Data on one's parents may serve varying purposes (for example, one's parents' level of education could provide some insight into where education might lie in a family's list of priorities; this can be useful information for providing a context within which to understand an application).
The comments provided in this forum are intended to provoke reflection on what might be important aspects to address in an application. Naturally, no student will be able to clarify exactly what criteria are used in selecting candidates for admission because the process is, in a way, more art than science. While there are some qualitatively-described criteria that should be obvious (ability to handle rigorous academic coursework, demonstrated leadership ability/potential, etc.), there isn't a fixed scale against which candidates are assessed. A lot of it depends on how an overall application package is perceived, and how that application package compares to those of the other people who apply in a given year. AdCom does not seek just to tick off boxes against some set of objective qualification criteria, but to think of the applicant as a unique individual and how they would fit as a piece in the puzzle of a diverse, engaging class.
To some extent, yes, there is an element of luck. As applicants, we cannot control who else applies. But I would contend that the vast majority of the application process is under your control (how you choose to put your application together, where and how you choose to interview, how much you do in research into Wharton, how much introspection you perform, how well you do on standardized tests and previous academic coursework, how effective and accomplished you are in your career and extra-curricular activities, etc.).
Regards,
Victor M. Lee
Class of 2011