What we refer to as ‘races’ are racialised groups of people.

Racialization is a complex and multifaceted concept that has been used to describe the process by which certain groups are categorized and treated as inferior or superior based on their perceived racial or ethnic identity. This process is deeply rooted in historical and contemporary power dynamics, shaping societal norms and cultural identities.

source

So it’s the society you live in that defines what groups of people get racialised and who belongs to that group. In the US and Europe, racialised groups include Arabs, African descended black and brown people, Eastern Asian people, Southern Asian people, latinx people, Native Americans, Roma/Sinti people, etc.

Since racialisation is purely a social construct, the people who get racialised change over time. Italians used to be a racialised group in the US but are now considered ‘white’.

With white, people usually refer to the ‘in-group’ of a society (from a US and European perspective). Being white means that you are not racialised. The answer to the question if someone would be considered ‘mixed’ if they descend from both England and Swedish is usually no, because English and Swedish people are considered white and don’t face characterisation or discrimination based on how they look.

Racialisation is unscientific and a form of discrimination. It’s a fact in society and it’s important to be aware that some people get racialised and thus treated differently based on their appearance, but trying to characterise people in a set of ‘races’ is not scientific because it is purely based on something as subjective as appearance.

Your question assumes race is a real thing and not just something made up by people.

Cultures and communities are real. There's Native American culture, Indian culture, Swedish culture and English culture. There is no "white" culture. It's the clash of cultures than normally causes the problems we see in the world that we mislabel as "race".

someone who is English and Swedish would not be because they are just white

Nah that's still a mix, a mix of two things commonly referred to as 'white' currently. The standards of 'which races are white' has changed over the last hundred years.

Racial categorization (a.k.a. race) is defined by a system, so the answer to your question is always relative to the system you are referring to. In the USA today, there are exactly 5 racial categories: white, black, Asian, Native American/Alaskan Native, Pacific Islander/Hawaiian Native.

https://en.wikipedia.org/wiki/Race_and_ethnicity_in_the_United_States

There was a time when there were three racial categories. Other systems have other categories.

In your example, under today's rules in the USA and indeed under most systems of racial categorization, someone with Swedish and English parentage would be categorized under the white racial category and be of mixed ethnicity.

Races are mostly arbitrary groupings, based on skin color more than anything else.

Ethnicity, however, is less arbitrary, but still contains some arbitrary factors. It's usually going to be based in culture or national origin, depending on who's using the term.

So, Swedes do have their own ethnicity, though you'd find arguments exactly what ethnicity they'd fall into, but it would likely be different than Brits.

Ojibwa people are very different culturally from, say, Cherokee people. There's even a good degree of common features that vary. But some people will still try to lump them together as "native American", even though that term is almost as useless as "white" or "black".

Truth is, we're all mixed to some degree. Except maybe the sentinel island peoples, or other isolated groups. Even then, it isn't like they didn't get to wherever they are without traveling, so they mixed with something along the way, even if you have to go as far back as when Neanderthals and what gets called modern humans were still fucking.

That's part of what makes ethnic groupings partially arbitrary. It's unusual for no movement between groups to occur, even across pretty damn brutal landscape barriers. Big rivers, mountains, they aren't totally impassable. Even deserts can't keep humans from fucking each other in small numbers as they travel.

However, you can usually go with nationality and ethnicity being linked, though there's so many exceptions that it's absurd to do so. Just look at Nigeria and try to sort out the various groupings there and not notice there's barely an overall national connection between them. And that not everyone in those groupings are even all in Nigeria to begin with.

The confusion should be the lesson but oh well.

It depends on who is talking about whom not where they came from or the color of their skin.

Quit operating under the three fifths compromise.

Metis

https://en.wikipedia.org/wiki/Metis