Linking to an associated website

I have a client who is a photographer and has a main website which has weddings, portraits etc and another website which has boudoir photography. Both sites are totally separate and on separate servers. Would a link from the main website to the other website be considered a link to an adult site and downgrade her rankings?

It is hard to say if the other site is classified as adult or not.

If you do a search that the other site should show up for, and you have safe search turned on, does the site show up?

Yes, it can be the reason of one negative point to eye of Google because both are irrelevant website…

Hard to say without actually seeing both sites. In order for your site to be penalized by Google, the other site new to be or border on being a full blown porn site.

ya based on single server it might be effected