writing across the genre lines......

Um, I can't answer this, and I guess someone will move it elsewhere.

Grisham comes to mind.

From the perspective of a school librarian (I'm not one yet but almost there) I think it would depend. I am giving this perspective because where are you going to find children's lit but in a public or school library? When it came time to order, I'd ask myself if I thought parents would recognize the name. Heck, I may not even know better myself, lol. Most of the time, it wouldn't be an issue. I think that unless someone is looking to reconsider a book because they disapprove of the content, then most parents pay very little attention to the collection in the library as a whole. What they do notice is when a book has controversial topics in it. For example, some parents get up at arms about Harry Potter or the Twilight series. I live in a very conservative small town. But pulling books is a drawn out process with forms and committee meetings, blah blah. Censorship isn't easy, even in a tight-knit community such as mine.

What I would suggest to be safe is to have two different pen names. If you publish under two different names you never run the risk of Sally's mom who loves steamy romance recognizing your name when her daughter brings home a delightful fiction book and asks mommy to read it to her at bedtime. Just my 2 cents of course. I'm new here too.

Moving this over to the Roundtable forum, where, I suspect it may be a better fit

If you're worried that your "adult" books will hamper the popularity of your children's stories then write under two names. The downside of that is if it becomes known people may/will get the sense that they've been had, then your screwed.
C

Neil Gaiman springs immediately to mind as someone who writes kid's books along with some seriously dark adult fare. Ditto for Michael Chabon. They have a cult of personality behind them, though, and they can throw their weight around, I bet. They were established well before they tried kids stuff, and also their earlier fare did have some child-like leanings to it. (Comics in both.) Not sure if that helps.

Meg Cabot writes for both kids/YA and adults I think. Stepheny Myer writes YA and Adult. So yeah it can be done.

It varies between genres. It's common for fantasy/science fiction authors to use the same name for their adult and child stories. It doesn't appear to be very common among erotica authors.