Answer by Raakhee V. Menon:
If Karna was not let go by Kunti, then it makes sense to assume that she would have admitted to her folly and brought up her illegitimate child in the palace itself, because putting a child up for adoption was not very popular those days. Duh!
He would have grown up in the midst of luxury, and yet be considered at a lower level than the other royal children owing to his ‘questionable’ siring. A child born out of wedlock is never like ‘legitimate’ children, even if his mother is the princess of the land. So Karna’s identity crisis would still have been an integral part of his character. Who would have believed that the Sun God had sired him? Nobody.
And he would have lived his life hearing that he is the by-product of a mistake his mother committed in her youth.
And would the teenage Kunti have remained in the palace to look after her child? No. When the time came, she would have been married off to any suitor of noble birth who was willing to accept an unwed mother. This would have made her chances of ever marrying into the Kuru family very bleak, for they were well-known for marrying very high and they left no stone unturned to see to it that their men wed the best princesses in the land. Even a blind prince Dhritarashtra was married to a fair maiden like Gandhari. Would they have agreed to a match for their crowned King with a princess (who was already only an adopted child) who had mothered an illegitimate child? I don’t think so. They don’t have a very impressive history of treating their womenfolk right anyway.
So that rules out Karna ever being a part of the Pandavas. And how would he be a Pandava at all? A Pandava is a ‘son of Pandu’. Or at least the boys were born while their mothers were wed to Pandu.
What of Karna? Kunti had no relation with Pandu when she had Karna. Even if she had married Pandu and even kept the child with her, he would still not be a Pandava. He would be outsider even then.
That said, what would that have made of young Karna, left to fend for himself in a palace that was home and not quite home at the same time? A rich and angry young man.
He would have been entitled to the best education (along with the other children of the household) but his character would have been just as flawed. He would be a child growing up without the love and care of a proper set of parents. He would probably have grown to hate every woman because of what one woman did to him by bringing him into this world and leaving him for the pleasures of a more socially accepted marital life. He would have been a lot worse than what he actually turned out to be. A father-less royal with a lot of money in hand and a lot of scorn in his heart is the start of a merciless tyrant.
One of the main reason why Karna was a brooding and quiet character is (I feel) that he was deeply affected by his ‘lowly birth’. He felt like a misfit everywhere. Such feelings often got the better of him and they served to be his controlling mechanism in the long run, i.e., it is these very feelings that held him back from becoming the all-powerful tyrant that he could have become. At least, he grew up in a humble home with simple loving foster parents to whom he was the world.
For all the pain and insults he endured, this was a luxury most of the other royals didn’t enjoy…the warmth and care of a loving set of parents who loved him unconditionally.