You can find the answer to this question in Chapter One of this excellent novel, when Victor begins his account to Walton of his life and the curioius series of circumstances that led him to his chilly and inhospitable surroundings. We are told in this initial chapter of Victor's parents and how they met, but also how they treated their first son. Consider the following description of their relationship with Victor in his childhood:
I was their plaything and their idol, and something better--their child, the innocent and helpless creature bestowed on them by Heaven, whome to bring up to good, and whose future lot it was in their hands to direct to happiness or misery, according as they fulfilled their duties towards me.
The phrase "plaything and their idol" seems to point towards the way that Victor was spoiled by his parents. Although this word is never used, it is clear that the way in which Victor formed the central part of their life indicates that he was a rather spoiled child.