You keep harping on what things mean "to Americans." You do realize I'm American, right?
Marco Rubio's parents were both born outside the United States. Nevertheless, no one questioned that Marco Rubio was American, and being first generation didn't prevent him from running for president.
That's about as far from the point as you can be. Rubio was born in the US. His parents are neither here nor there. I was comparing the US requirements to people who became heads of state despite never having even lived in the country in question, who were invited from afar in a request that boiled down to "hey, will you please move here and become our king? We're not happy with the options we have in-house and you look like an alright guy. Thanks!" IIRC, the first time Jean Bernadotte ever stepped on Swedish soil was when he moved there to take the throne (well, technically, to become their aging king's crown prince). He was invited by the Riksdag on the basis of his skill as a military leader and the kindness he'd shown to Swedish prisoners of war.
I happen to find that fascinating, precisely because I'm American. Even if you moved here as a child and have been a citizen your entire adult life, you aren't eligible to run for President unless you were born here. A naturalized citizen can be a governor, like Arnold Schwarzenegger, did, but the highest office is off limits if you're foreign born. So yes, Marco Rubio could run for President, but his parents never had that option.
You find this silly. Fine. It's not for you.
No one is saying the Bernadottes are less than or don't have a right to the throne. It's just interesting to see that, even if you look at generation after generation after generation of monarchs in this dynastic house and their partners, this century was the first time that someone in line to their their throne chose a spouse from their own country.
Especially given that they started with the importation of a foreigner to the throne.
That's noteworthy because the first however many generations of the house were living in an era when (a) royal marriages were first and foremost political, (b) monarchs still had a degree of power, and (c) politicians tended to have some concern that a monarch with strong familial or cultural ties to another country might offer an unwise level of favor that country of origin in international disputes. That concern wasn't helped by the very small amount of contact royals used to have with their nations' people. Given that context, it's remarkable to me that the Bernadottes never felt the need to shore up their "Swedishness" by, for instance, marrying off one of the first Bernadotte heirs to a princess from the prior ruling house.
This discussion has lead me to read up a little more on the family, so I now know that Jean Bernadotte himself made a choice that probably made a very big difference in how accepted his family was by the Swedish people: when he decided to accept the offer of the throne, Bernadotte went to Napoleon to offer his resignation and ask to be emancipated from his French citizenship. Napoleon tried to make him promise never to take up arms against France. But Bernadotte refused to make that pledge, saying quite firmly that he was obliged to consider the needs of Swedish ahead of his own Frenchness or ties to Napoleon.
Bringing him in had been a Riksdag plan; the king didn't much like it. But Bernadotte won him over after he arrived in Sweden. He seems to have worked pretty hard to earn his status as an adopted Swede. He was running everything even before the old king died, and he was popular. In other words, he really did do the work to become seen as Swedish.
The lack of Swedish-born brides in the family tree could have been a sign that generations of the Bernadotte house holed up in their palaces and didn't care to mix with people from their country. It's nice to see that, in this case, it was actually a matter of them not needing to make that kind of political statement with a marriage because the founder of their line did a good job of making the Bernadottes Swedish in ways that mattered to the nation's people and politicians.
And that's why I like these conversations. Little questions like the one that started this send me off along rabbit trails of data, the details of which hint at a nation's political story and help me find interesting times in their history that are fun to learn about.