I hug all my grandchildren as soon as they walk in the door, I’ve hugged them from day one, 3 of them are boys now...9,10 & 12. I’ve had a few occasions were they’ve ran past as they’ve come in the door, but I just call them back and give them a big squeeze, sometimes it’s returned or sometimes they’re in such a hurry to fuss over our dog it’s half hearted. I don’t ask them for a hug, or ask their permission to give them one, I’m a hugger!!! I give them one and perhaps a few more while they’re in, then I do the same as they leave. I will admit the best ones are when they just come to me and give me one. I’m puzzled why he’s being a bit mean to you, and who doesn’t want their grandkids to love them, but I’m the type of gran that ( even at 6 years old) I’d ask him why, and if it was just a simple “I don’t want to” I’d say “ ok” and leave it at that. Sometimes children recognise our needs and can play up to them to have a bit of control, so don’t fuss or attempt to try too hard to get round him. Ignore it ( as hard as it seems) and he will come round or just get through this wee phase. I wouldn’t let him dictate whether you hug his little sister, and I wouldn’t let him off being cheeky, he would be told in no uncertain terms, being rude isn’t acceptable. If I knew I hadn’t done anything wrong to make him behave this way, I wouldn’t let it get to me. He will settle, he’s only 6... so still a little fish trying to swim ahead of himself.