The answer to this question can be found in Chapter One of this incredible and memorable novel. This chapter narrates the first visit that Lockwood pays to the owner of the house that he is renting, Thrushcross Grange, and his impressions of the misanthropic Heathcliff and of his abode, Wuthering Heights. Consider the following quote and the gothic details that we are presented with:
Before passing the threshold, I paused to admire a quantity of grotesque carving lavished over the front, and especially about the principal door; above which, among a wilderness of crumbling griffins and shameless little boys, I detected the date "1500," and the name "Hareton Earnshaw."
Lockwood goes on to say that he would have liked to inquire for more information about the history of this date and name, but the surly and reticent disposition of his host did not exactly encourage his inquisitive nature. Thus the name on the threshold is that of Hareton Earnshaw, and the history is something that the rest of the novel will come to reveal.