They go hand-in-hand. Surnames aren't gendered. Names that reverse gender are often surnames used as given names.

"John" or "Matthew" are probably never going to become female. Nor will "Elizabeth" or "Katherine" become male.

"Spencer" was male when Spencer Tracy was a big name. Today it could go either way. As a family name it relates to the profession of a steward.

Surnames are gendered in some languages, typically when they're defined as gendered adjectives.

In Polish '...ski' is masculine and '...ska' is feminine. The prefix stays the same, so a brother and sister have slightly different surnames. (Like 'Wolski' vs 'Wolska.')

In the US some immigrants forgot this, so you get American women with a '...ski' surname.

Good point. I think Russian surnames are the same right? (Ivanov/Ivanova etc.)

Is it common in these cultures to use surnames as given names?

Those aren't family names but rather patronyms or matronyms (respectively); they directly translate to "son/daughter of Ivan". As I understand though, matronyms are often based on the name of the person's mother, so Ivanova wouldn't be a common name.

That said, I don't speak Russian and have only a passing familiarity with the construction of Russian names, so don't take this as gospel.

I don't think so. https://en.wikipedia.org/wiki/Ivanov says it's a surname, equivalent to "Johnson" (since Ivan is Slavic for John).

In the old days Johnson might've meant literally "son of John" but no longer. All of the people with the surname "Ivanov(a)" on that page also have a patronym, which in the West would be considered a middle name.

GP is correct. Ivanov or Ivanova would generally be surnames, whereas Ivanov or Ivanov[n]a would be patronyms. In Russian culture, they generally don't use matronyms. And yes, it is indeed common in Russia to refer to individuals whom you are not close with using their surname, similar to Japanese culture.

Only ever heard of matronym use as a joke or very archaic.

Referring with surname only is a hierarchy assertion thing, and somewhat rude - boss would talk down to subordinate like that, or teacher to student. When talking "up" or "sideways", or "down" but without a desire to assert superiority a name+patronymic is usually used, which reflects a respectful distance while not slipping into rudeness or overt familiarity. Sadly, it is mostly disappearing and giving way to Western "name-only".

And then, to emphasize familiarity, some groups adopt way of referring to each other by patronymic only :)

Patronyms, derived from name Ivan would be Ivanovich/Ivanovna

Generally, -vich suffix is used in masculine form and -vna suffix in feminine form.

You are right, my bad.

In Iceland, patronymics are also gendered and may sound quite familiar: "Björk Guðmundsdóttir" is their most famous example today.

In high school, we referred to our teachers by honorific and surname, and we were also addressed by surname, even by our peers.

When I rewatched the Harry Potter film series this year, I began paying attention to how Harry was addressed. Draco Malfoy called him "Potter". So did many teachers, "Mr Potter". He who must not be named called him "Harry" and many epithets like "the boy who lived". Hagrid and Professor Dumbledore, at least in private, called him "Harry" all the time.

This is especially interesting, because "Potter" is a homophone with the Latin Pater, meaning "Father".

They did not necessarily forget the rule, it’s just inconvenience, especially when dealing with official business, when you have to explain why (for example) your kid’s last name is slightly different than yours.

I don’t think it’s only that, but in many Western European societies (and those derived thereof) it would have been unusual to have members of a family with surnames spelled differently, even if only the suffix.

So the whole family may just have taken the male head of house’s surname to avoid problems, or even been simply assigned his surname by immigration officials.

Many a name were changed at Ellis Island, for example.

A surname ending in “son” could be seen as at least a little bit gendered.

You'd think so, but Allison is firmly in the girls camp today, at least in the US (Liverpool FC's male goalkeeper Alisson Becker is Brazilian). Madison is also more associated with girls.

Surnames or occupations (Tanner, Cooper, etc)

You never know, OP's son might one day work as a valet.

s/Never trust a man with two first names/Never trust a man with two last names/.

My sisters both have last-name first names that are commonly used for both genders, and one of those sisters has 3 kids, all with last-name first names. It's weird, but it beats everyone having a biblical name.