Being from a single-parent family is hereditary. In my case, I got it from my father, who left my mother before I was born. Like most hereditary conditions, from time to time, you’ll find yourself discussing it in circumstances you can’t control and in a manner that makes you mildly uncomfortable. In my case, well-meaning people ask what my father does, which leaves me with the unlovely choice between honesty, which makes the questioner feel awkward, and lying, which is hard to keep up for long.