Maybe that question was a psychological exercise rather than a practical one. Look at this from the perspective of the three children - you're cycling down a dark road, suddenly a masked man jumps out at you with something in his hand that looks like a gun. He orders you, in a very threatening manner, to lie face down in the ditch. At that stage, you are going to be very frightened, and possibly even in fear of imminent death. So then he points the possible gun at your head and asks you a question - any question - whether or not you answer, and how you answer, will tell him something about you.
If any of the boys had responded to his question with something like "none of your business", that would have told him that the child in question was rebellious and difficult to control. But even without going to that extreme, tone of voice can give away whether or not someone is frightened or angry or rebellious or whatever other emotion. So possibly that was the reason for the question.
That's kind of been my thinking on the subject. Like I said, it's my thinking that he didn't really need to ask, to get their approx ages, and/or, as a pedophile, he didn't need to know their ages in order to know which of the three he wanted, and, he could tell that Trevor was younger; actually, in pictures of the three, it's kind of amazing how Trevor looks almost a couple of years younger than the other two, because of his height if nothing else. But, my original thinking, before finding and coming to the board; which even from watching "The Hunt" and whatever else I'd read on the subject, like Joy's blog, it's an obvious interest as to why he chose Jacob and not one of the others; and also, why he asked their ages. I somewhat suspect that he wanted to take out "the strongest link" in that, maybe if Jacob appeared more solid, and less shaken up, then he may have felt that Jacob would have been able to give the best description of both him and whatever other circumstances that may have been able to identify him, and/or, that Jacob may have been the most likely to get help the quickest of the three. Maybe Jacob would have run straight to Merle's house, just a little closer, and Merle could have made the call that much quicker; not that the perp would have known that; but, that he wanted to preclude the strongest link from seeking help as quickly as possible.
I suppose that it has to be considered that, what if he did know Jacob, maybe even to some very slight extent; but, that he thought that possibly, over time, if he let Jacob go, that Jacob would at some point recall where he knew this guy from. Maybe of the three, there was some chance that he had been around Jacob, even to a very slight degree; but, the other two, he knew that he'd never been around them; so, they'd never been around him, and so he asks the questions in order to keep someone from considering that. In other words, maybe if he'd asked no questions, then, investigators, may have speculated that selected Jacob right away because he knew Jacob, and 1) Jacob was his target, and 2) Jacob may have known who he was; but asking questions then draws all the attention to, "why did he ask their ages" and "why did he pick Jacob, of the three" which is certainly where the attention has been.
One example that comes to mind here is the case of Elizabeth Smart, where, quite a long while, several months, after her abduction, her younger sister, at some point, kind of suddenly realized and remembered who the guy was who had taken Elizabeth. A handyman who had evidently spent some time around the house. And, she was a young girl. Possibly if Jacob had just been around this guy to any extent, and the guy took either Trevor, his younger brother, or Aaron, his best friend; Jacob would've racked his brain continuously, and at some point it may have come to him.
I actually have one more thought on that, as far as whether he thought that Jacob may have been "the strongest link" which is; as far as I know, we don't know, for a fact, whether he had any way of knowing that Jacob and Trevor were brothers or not; maybe one of them had said something, I don't know. But, whether he knew that or not, he could have perceived that Jacob was in fact more solid, less shaken up, and may not have been so easy to convince to run off, leaving the other two or the other one. I'm guessing that's why he sent Trevor off first, the youngest, get him to run off, then, when he sends Aaron, he just feels like he's following Trevor, to some extent. But, maybe if he'd tried to send Jacob first, or second, especially if the guy was planning on trying to take Trevor, then he may have had to deal with a kid that wasn't ready to leave the other two, or either of the others on their own. It just seems to me, like these could 'possibly' be things that he considered under the circumstances.
