Does the anchor element have a nofollow attribute?
Does the page have a nofolow robots meta tag?
Does the robots.txt file prohibit crawling of the page?
If any of these are true, they are no follow.
If none are true they are followable.
I used to use numeric url parameters and was amazed at how the Google Webmaster Tools dramatically increased the number of web pages in their search as soon as pretty-urls were introduced.
If the variable don’t affect content and are just there for tracking purposes it can result in multiple instances of the page being indexed as different pages which can flag up as duplicate content.
To prevent this, use a canonical tag in the page head, you can also set up “URL Parameters” in Search Console and/or set the links to nofollow. Though you may want to links to be followed if there are no “bare” links to the pages anywhere.
I had to rename numerous duplicate page titles to ensure unique references. Canonical links were also introduced although I think it was unnecessary since the duplicates were eliminated.
What “disallow” means is that bots which respect the robots.txt protocol will not visit that page and therefore won’t see the content, including any links. It is not the same as marking links nofollow, although the end result should be the same.