Major/Big lines

Hi, I've been playing for a while, but I'm always confused when people on the trading center ask for either no major/big lines or they do. How do I tell whether a wolf is from a major line or not? Do I have to go through every single wolf in the genealogy? Do I tell from other things? When you reply please imagine you are explaining this to a complete baby (english isn't my first language and I want to make sure I understand things fully, thank you)

As far as I know you do have to go through the male names in the lineage to see if there are alot of pups from a particular stud. 

But as you look more and more at different wolves families you will start to remember which ones pop up ALOT for example Faelor & Koji