Someone recently suggested to me that if a photographer does, for example, family photography, but wants to branch out to something like boudoir/nude photography, they should use a pseudonym and/or create a second business altogether, to keep the two separate, and so that they do not offend or lose their current clients. What is the accepted rule about this, if there is one?
If your target market for family shoots is not going to be offended by using a photographer that also does boudoir, then you are probably fine to use the same name. Locale may be a factor here for local area values.
It would probably be worth it to have two completely different web sites, as it's incredibly unlikely that your family portrait clients will cross sell to boudoir. It's a cross sell opportunity to play at your discretion during or after the shoot.
It is more probable to sell family photos to a boudoir client, so advertising your family services on the boudoir site may not be a bad thing.
Tl:dr - the same name may not be an issue, but do create separate marketing materials.