Five years ago...
Being born as the illegitimate son of a noble was a shameful upbringing for the higher caste of society. One would be lucky enough if the legitimate parents and children were understanding and forgiving. That it was not the sin of the illegitimate child, but the parents who cheated.
However, that kind of scenario was rare. And the most common thing, was the usual drama of the legal wife and children, giving all hardships to the illegitimate child. While the patriarch turned a blind eye. Or in the vice versa scenario, it would be the mistress and the illegitimate children, who would make hardships to the legitimate ones and scheme to get the rightful inheritance that should belong to the legitimate ones.