Writing competitions ask writers not to put their name on their manuscripts, so there can be no question of the judges being influenced by their identity. Most writers would dearly love to be so well-known! Competitions aside, there is a school of thought that if you're proud of your work, you should stick to using your real name and not a pseudonym–not least because you want any royalty cheque to be accepted by your bank–but there are many instances when a writer might choose to use a pen-name. If they do, they'll be in good company.
Some writers use a pseudonym because they think the alias is more attractive or easier to remember. It could be that they want to hide their authorship from their everyday life. Mark Twain's real name was Samuel Langhorne Clemens and Hector Hugh Munro chose to write as Saki. The aliases are certainly snappier.
The Brontë sisters used male pseudonyms to hide their identity and their gender. In their day, the thought of a parson's daughters writing such passionate and free-thinking novels was scandalous. Unfortunately, such prejudices linger, although they aren't as extreme as they once were. There's still an expectation that action-thrillers are best written by men and that romances are written by women. A way around it is to use your initials and surname, and leave people to draw their own conclusions. Of late, there's a trend to ask authors to put their preferred pronoun on their submissions, which may or may not give the game away.
In my case, I use my initials because so many people (including relatives) have always got my name wrong. There have been a few instances where I've been published as Karla Dearsley because the submission was made via an online form which wouldn't accept initials as a forename. Lately, I've been wondering whether I shouldn't use Karla Dearsley when I write outside the speculative genres. Readers seeing K. S. Dearsley probably expect my writing to be Fantasy or SF because most of my published work has been that, but not all of it.
If I used Karla Dearsley for other genres it might save confusion. This is a tried and tested solution for the likes of J. K. Rowling (Robert Galbraith) and Ruth Rendell (Barbara Vine). Why stop at one pseudonym? I could use a different one for plays and poems and mainstream literature or historical fiction. I have no shortage of potential pseudonyms to choose from. As I said earlier, people constantly get my name wrong whether it be my first, maiden or married name. I could use Clara Beardsley, Karen Greaves, Caroline Dursley, or even Carlo Jeffs.
The problem with that is, I'd never build a following, and might even develop a split personality trying to keep up with all the different mes. (Carlo Jeffs sounds like an Irishman with an Italian mother–and yes, I really have been called that.) Maybe I should postpone worrying about it until after K. S. Dearsley has made a name for herself.