You're reading the section wrong; what you quoted is called "flush language" which explicitly states in the very first line, "In addition to........subparagraphs (1) through (5)" and then goes on to address other types of taxes.
Again, there is no requirement that real estate tax be levied on anyone with an interest in property before the taxes paid are deductible in the tax year they are paid. It is irrelevant that the taxes were never imposed on the "offspring" as that person has an ownership interest in the property and, without payment thereof the tax lien could be foreclosed and the property sold.
I'm really not sure why you're arguing this point as it is fairly well-settled.
