Sorry, Dave, but he's cold reading. He's doing it in a way that's clearly not obvious to you, and it's entirely reasonable to assume there's no malice or insincerity on his part. It's likely he's not aware he's doing it (which is fairly common among amateur "psychics"), but he's doing it all the same.

Peace Makes Plenty is right: it's not only about asking leading questions, but rather building upon the feedback you get while throwing out guesses. Confirmation bias, always present (especially if you're someone who wants to believe in psychic phenomenon), means that misses tend to get ignored while the occasional grazes tend to be interpreted and/or remembered as hits.

Reading body language is a skill like any other. Some people have natural talent at it. Some can be trained at it. Some will always be bad at it. It would not surprise me if your brother turned out to be a better-than-average Poker player.

It isn't especially hard to test psychics using proper scientific controls, controls that will both recognize legitimate psychic ability while simultaneously preventing attempts at fraud.

Far less formally, it's quite possible to turn the tables on cold readers (both amateur and professional), and manipulate the reading to some extent.

Story time. --------

One time in particular, I met someone who fancied himself a natural psychic, and who insisted upon doing a reading for me. (I wasn't especially interested, but wasn't entirely unwilling to go along with it, to a point.)

This guy was an amateur, so he wasn't consciously cold reading in order to scam me for money. (Well, actually, he was trying to scam me for money, but the psychic bit wasn't part of that. That was just a plea for my approval. I didn't get the impression he was able to keep friends, so much as a small circle of sycophants on retainer.)

The idea of the reading was, supposedly, that if I were to pick two people I knew with the same name, and said each (same) name while thinking alternatively of these people, he could tell me about them.

During the reading, I gave him as little verbal feedback as I could get away with, only answering direct questions, and being careful to not volunteer information.

I was also careful to put on my own poker face. Not because I'm good at guarding my reactions. In poker terms, I'm a fish. A fool to be parted with my money. But I am also, however unskilled, someone who has enjoyed a long fascination with stage magic, psychology, and security, particularly when combined.

It should have been quite obvious to the amateur psychic that I was a hostile readee and that I was attempting to smother my reactions. What wasn't immediately obvious to my host is that this was very much the image I intended to portray. The poker face was pure misdirection. I can't hide my reactions very well, but I learned long ago that I can lie with my face.

Now, I let him go for about half the reading without actively lying to him, but without volunteering information either. During this half of the reading, he had no hits. The only time he grazed was with statements that were so vague as to be without content.

For the second half of the reading, I gave him feedback using my face. A slight quirking of my eyebrow. The barest curl at the corner of my mouth. Subtle widening or shifting of my eyes. Altering my breath just a bit. That sort of thing.

I found I was able to exert a great deal of influence on what he was making up about my friends. He was quite willing to follow the garden path I laid for him. There were no hits, by the way, during this section of the reading. He never came close.

Now, this story is purely anecdotal, of course, and there were no scientific controls whatsoever on the pseudo-experiment I pulled, but it's pretty clear this amateur "psychic" was just a natural face-reader whose ego got ahead of him. (Well, that wasn't his only problem by any stretch, but the rest of it isn't relevant to this thread.)

End of story. ------

Your brother, Dave, may simply be a natural face-reader who has made a few especially memorable, but statistically insignificant guesses. Probability guarantees someone's going to guess right if you throw enough guesses (or people making guesses) out there. It's the same law of probability that allows folks to win every lottery, just about every week, despite the hideously long odds against an individual win.

__________________
And you, to whom adversity has dealt the final blow
With smiling [faces] lyin' to ye' everywhere ye' go
Turn to, and put out all your strength of arm and heart and brain
And like the Mary Ellen Carter, rise again.