They're big talkers, with good reason. Did you imagine then, when you were little, that you would be telling small stories about yourself one day? How can you stop yourself? The moral of the episode isn't persuading yourself that the opposite of everything you thought then really was; it's reminding yourself that the reverse is true, too. After all, consider a man in his twenties or thirties. To a very large extent, he's just articulating something he thought in his middle age, mostly for the benefit of his family.
But what, really, is it that people said about themselves when they were young? It's surely logical: what formed your sense of self depends largely on the people in your family, as is surely true for parents. But what? Presumably you were told your little self-portrait was an accurate impression, and far from being paranoid, thought this was reality, and shared it with your loved ones, as people do, perhaps, in passing. But how could you have doubted that was true?
Your view that your family's self-awareness was good seems plausible because in your head, so was their assessment of your abilities. Here's another famous memory: a couple of years ago, I was in a crowded restaurant, minding my own business, when an elderly man in a bowler hat entered, declared I was "beautiful" and grabbed my arm. My girlfriend and I suddenly found ourselves a captive audience, because he'd bought a large portion of the meal. And you know what? I was taken aback, and thought him charming; my girlfriend felt differently. I knew he was probably right, for obvious reasons, but didn't like that he'd reminded us of that.
This highlights one of the baffling things about the human race: it seems to be a self-perpetuating mob. People believe they're saving their lives by clinging to a mastacle, but if it falls into the ocean, they stand at greater risk of drowning; if they're sailing at night, they're more likely to have a freak shipwreck; if someone's bear-ambushed them, they're more likely to get it over with. Life is, fundamentally, messier than the odds would suggest.
Clearly, we ought to learn to better cope with these perils. But surely it would be better to be able to see our circumstances as more complex than we admit to ourselves. When we had a close call at the turn of the millennium, for example, I'm sure some of us subconsciously tried to reassure ourselves that somehow we were safer, and that those pesky moths and gales wouldn't beat us. We could well have been unconsciously trying to compensate for the information we'd taken from our emotional family members. But those thoughts remained within our head, unlike the truth - which is that we were probably better off naked.