Is it rude to ask someone's age?

Yo, I hope not. So the new teacher we're expecting in January... I've been really looking forward to his arrival. I haven't mentioned Russ in a while, but I seem to have crossed the line at last and am finally able to treat him amiably. This is good news, because he's a very good man, just... he used to be a little frustrating to me. Anyways, we got news of the newcomer a while ago, when Russ was still planning on leaving. He's recently changed his mind though, so it sounds like there will be 3 of us here after all. I got a glimpse of his letter of recommendation, and it made him sound pretty impressive. Additionally, I was told that he was only 24 years old. Not only fresh meat, but young blood! All right, this evening has been too much about pork, sorry. Uumm, but yeah, I was really hoping for someone that I could relate to... more. But now this person's age is in like, limbo. Apparently there are two people who applied who have the same name, one of whom is older and the other is younger. We're all (as in, all 5 of us even remotely involved in this conjecture, though Alice and I are the only ones who really seem confused) sure that the young one is the one meant to come. But in a message I got recently, he alleged that he was a 12 year old in a 53 year old's body. And I'm like... that's not something you say unless your body is 53 years old, unless maybe you're... prematurely balding, arthritic, or otherwise... well, disabled or something. Or maybe you smoked. A lot. I don't know! We even took the average of those two ages and that's like 32.5. Then, when Alice and I asked Russ what he knew, he said that he'd heard that this person is about 30. I'll hopefully know for sure shortly, and you can bet that I will share that information immediately, whether it's socially appropriate or not.