A thumb-sucker

I love the fact that my youngest son sucks his thumb.  I love it for practical reasons; that he can soothe himself easily and that the simple act of finding this amazing digit can take the noise level in the house from storm force to silent in just a few seconds. I love the index hooked over the nose and the fact that he can find it in his sleep and sometimes, when I'm dressing him, he will agree to remove it from his mouth, only so long as it takes to put an arm in a sleeve.  I love it because he looks so sweet; his big pupils widen a little as he brings his hand to his mouth and then he settles in to a silent pulse.  He often brings up his other hand in prayer-like support, interlacing his fingers and holding on fast to the little finger of his sucking hand. I've noticed too that when I pick him up, he often pops his thumb in his mouth as if to reconfirm the safety of my arms.  He's putting the keys in the door.  He's home.  I love trying to make him smile until his suction goes. I love the thumb's over-sucked wrinkliness when it is not in his mouth and the strange fact that I never need to cut the nail. I love it because it so clearly tells me his mood.
I think Max hates it for as many reasons.  I've spied him giving it a go, trying to see what Oli takes from it. He puts his dry thumb in his mouth and, with a look of mild confusion, takes it out again, as if someone has asked him to chew clay.  There is no pleasure, no comfort.
'I don't want Oli to suck his thumb!' Max will declare when we are driving somewhere. He wants an accomplice on the back seat. But the two boys have different ways of dealing with the restrictions of car seats. Max wants music to take him somewhere interesting, Oli wants his thumb to take him off to sleep.
I love the story I was told of a friend who, as a child, had so many toys on her bed that every night, she tucked them in under her duvet, then, in the absence of a place to put her own head, would curl up to sleep on the floor.   Max's bed is not dissimilar; a muddle of dogs and cows and lions and bears and some woolly birds.  His dirty blond teddy with the fading blue ribbon round his neck is Oli's thumb in the mouth. For Oli, soft toys are batted away as an irritation.  All those carefully selected rabbits and elephants, given before we realised what kind of boy we had amongst us, are piled up, untouched, in a withy basket in his room.
I wonder what these differences portend. If anything. Are the thumb suckers of this world more self sufficient? Do teddy lovers crave more support from others? And were does it leave the rest of us who remember neither, except perhaps, an old raggy?