A Japanese person was asking how to tell the gender of someone based on their name. Someone else claimed that if it ends in "a", it's usually female, and if it ends in "o", it's usually male. How reliable is this rule? I suspect it's only true of names derived from Italian, but I could be wrong.
Assume that the names are of people of European descent in western countries such as America, Britain or Australia.
Short answer: you can't. There is no reliable rule that will cover all the various languages and exceptions and parents who name their daughter Maxwell and their son Andrea.
Longer answer:
The bad news is, the -a vs. -o ending rule has so many exceptions that it's useless. Bella is female, but Bela (well, technically Béla) is male; Andrea is male in Italy but female elsewhere; Luca is male in Serbia but female in Hungary; Consuelo is female; etc.
The good news is, there are some tools you can use.
However, the bottom line is that even after all your best efforts and web searches, you simply will not be 100% correct, because Parents Are Crazy. And they're increasingly getting crazier - in the US, even traditional masculine mainstays like Charlie are starting to skew female. So the only foolproof method to determine a person's gender is to ask.
There's no infallible way of divining someone's gender from their name. I once knew a woman named "Robert", not "Roberta". Evelyn Waugh, a British novelist, was a man. Bela Lugosi was a male actor. I'm sure others can come up with far more names like this than I can.
There are many "unisex" or "androgynous" names shared by males and females alike in the Western world. Same goes for Chinese and even Japanese names. It's often possible to determine gender from a person's given name, but not always.
If the name begins with "Mr" it's a male, if it begins with "Ms", "Mrs" or "Miss" it's a female.
It's tricky. In my opinion, we can't predict gender based on names alone, as the same names can be named for both genders at times. There are so many names that can be named for both genders.
On many occasions, it's not possible to determine gender based on name alone.
There are many exceptions. Many names are used by both genders. Here is a list of male names and a list of female names.
The -o and -a rule is generally accurate. From these lists you can see there are few, if any, male names ending in -a, while there are quite a few ending in o, and vice versa for the women. This will not always be the case.
In addition to the answers already posted, there is an extra spanner in the works. Even if names were unambiguously male or female, and had an easy, infallible way to determine which was which, there is still ambiguity.
If their name is the name they were given when they were born, it would only represent the gender that a person seemed to be at the time they were named. With gender being the mental identity of a person, it doesn't have to match their physical sex. Therefore, a person who identifies as female could have a name like "Bruce".
Throw in the possibility of people legally changing their name and/or physical sex, and there is really no way it can be relied on for identifying the physical sex of a person.
This must be true for any language; not just English.
