This is nothing more than my opinion but, with respect to federal tax research, Google is not your friend. Far too much of the information on various consumer-level web sites is erroneous, misleading, or incomplete. As a result, I would steer clear of those sites (Nolo, Nerdwallet, Investopedia, to name a few) and stick with the Code, Regs, RRs, RPs, advice memos, et al. Frankly, I hesitate to rely on IRS instructions and publications since they have been wrong in the past and they're not authoritative (I only cite them as a guide).
Regardless, if the son is the only potential heir, the whole issue here is less problematic. I would still, as did @Opus 17, suggest an in-person consultation with local tax or legal counsel who would have access to the deed and any other related and relevant documents.
