Some additional information from the replies, questions he answered:
Q: "There is no way to distinguish between them" so that means we can't tell their sex even if they were naked?
Y: Yes, exactly
Q: Do the same settings apply to the Viera from Ivalice (like in FF12 or FFTA)? Or is this a FF14 original setting?
A: The general settings are the same as in FF12, but I quit FF12 before we had the opportunity to publish these. So if you're asking whether this is an official FF12 setting, I'd have to say no.
Q: If we can't tell their sex by their appearance, but young Male Viera leave their village for their apprenticeship, does that mean there is another way to tell their sex?
A: There is a misunderstanding. They will only leave the village once their sex is apparent. You are probably asking this because you read "young" Viera, but because of their longevity, these "young" Viera whos sex just became apparent are seen as "young Children" by the other Viera
Q: What about their gender identity? Do they not have that on their mind while growing up?
A: They do not think about it until puberty starts
Q: So are they just accepting it after puberty? It sounds scary to me that onces they are old enough, they are suddenly being told "You're Male, you have to leave the village now"
A: For us a big influence while growing up is our environment, "As a girl/boy this is what you have to do and how you have to behave". In that sense, Viera aren't raised like that. Their approach to education and raising keeps this in mind. The surrounding enviroment is different to our present age.
Q: Are you going to play Male Viera in 6.0?
A: I am playing a Female Viera right now, but I will swap to a Male Viera in 6.0
Q: How old is Fran?
A: I can't tell you that....