Is it reasonable to believe Ma...

In nearly every discussion about the Perpetual Virginity of Mary that I've come across, the debate almost always comes down to whether the "brothers and sisters" mentioned a few times in the Gospels were biological children or if this was just an ancient way of referring to cousins (which I hold to). But what if it was neither? The past few days, I got the inspiration to realize that there is indeed another possibility that Protestants don't consider: adoption! Why not? Remember that the underlying actual goal of the Protestant side is to attack Catholicism by attacking Mary, so if the "brothers and sisters" aren't biological children then their anti-Catholic mission has failed. The adoption possibility doesn't seem to be an explanation that I've ever come across, which is strange because it easily counters the Protestant when they reject the standard Catholic cousin explanation. It was actually very common in ancient times for parents to die of diseases and such, since there wasn't modern medicine or sanitation. So it was not uncommon for children of the same region, neighborhood, relatives, tribe, etc, to adopt those orphaned children. Could this be why James, the "brother" of Jesus, speaks so highly of taking care of orphans? (James 1:27) The genealogy lists that Matthew and Luke give list different forefathers at some points, but this is easily explained by the reality that some of those sons/fathers were adopted, and thus lineages crossed, but since it was all within the same Tribe of Judah, it was ultimately the same lineage. What is a Protestant really going to do if you respond by saying "yes, but these were adopted children"? The Protestant will realize that they cannot simply presume, and thus their argument is instantly deflated. Plus, we are all truly the brothers of Jesus by adoption in the spiritual sense, and would even extend that into being adopted by Mary (and Joseph), which is how many Catholic spiritual writers have understood the "rest of her children" in reference to Mary in Revelation 12:17.