SEO optimization can be highly tricky.
Our customers ask us to add the nofollow attribute to inline related links.
In our opinion, this is not necessary, as says also Matt Cutts in this video.
How Inline Related Posts can help you improving your SEO
Inline Related Posts it was created with 3 goals in mind:
- Keep readers on your site
- Increase the page views
- Improve SEO
Is up to you choose dofollow or nofollow in the plugin setup.
As a human, you should just be clear in the related text of your boxes. Just alert users that box contain a related article and will not be a problem use dofollow link.