Recently, I attended a local writer's group because a literary agent was speaking to them. The agent told the group that each writer needs to think of him or herself as a "brand".
According to the agent, Stephen King started off as a "horror"-branded writer and that helped build his audience. Nora Roberts started off as a "romance"-branded writer, building her own audience before branching off into other things.
I like to write in different genres. Am I hurting any "brand" I might build? Should I write under pen names when writing material in different genres?
Or is the agent wrong?
It a real way, she's right, but it's kind of a Duh moment. Stephen King wrote what he enjoyed reading and writing, and so did Nora Roberts. They still do.
But keeping you name out there is important, whether it's your real name or a pseudonym. And you have to keep it out there in each genre. You can't write one mystery this year, one SF novel next year, and one Fantasy novel the year after that, and expect to build much of a readership, unless, of course, your novels all hit very high on the bestseller lists.
Whatever you publish, and wherever it's published is going to brand you. Every type of novel has a label. Always has. But readers like novels to come along in their genre fairly often.
The problem with writing in different genres under different names is How Many Novels Are You Actually Writing, and How Many Novels Are You Actually Selling?
If you aren't selling any, the question is moot, and it may be because you're diluting your talent, not your "brand".
It takes time to learn how to sell in any genre. It takes time to learn how to write a publishable mystery, time to learn how to write a publishable SF novel, etc.
Even if you are prolific, pseudonyms are still usually a good idea. Pseudonyms allow readers to know what genre they're getting by name alone. This is usually a very good thing, and it stops your own name from competing against your own name.
But the wider you write, the more prolific you have to be to keep a readership growing.
Anyway, first you have to sell a novel somewhere, in some genre. After this, reader/publisher demand will tell you how soon you need to write another novel in that genre.
If you're fast and good, you can write in as many genres as you have the talent to write in, but you have to meet this demand in each. And if they are different genres, pseudonyms help keep things straight in reader's minds.
But first, sell one genre to one major publisher. Until you manage this, nothing else matters, and to do this, you usually have to concentrate on writing a given type of novel until you get it right.