A child born to unmarried parents, the most neutral way of describing a child as illegitimate or a bastard.
"Natural child" sounds much better than "love child"; George Carlin put it, "I have a love child who sends me hate mail."

"Bastard" is too loaded and "love child" sounds silly, since the "love child" is often the unintended result of one-night stands where love hardly features.

At least "natural child" is accurate without any silly, infantile euphemisms or insulting connotations.
by Lorelili July 22, 2014