In English-speaking cultures, bastard can be interpreted as a person whose parents out of laziness or otherwise could not get married in time.
In Hindi/ Urdu, the word for bastard is haraam-zaadah, born out of illegitimacy. In India, respectable boys and girls did not interact at all before marriage. The only woman a man could come to intimately know outside of his marriage would be a woman of easy virtue. Therefore being born a bastard was not so much a comment on the marital status of one’s parents at the time of conception, but a slur on the mother’s moral character.