I'm somewhat new to this and confused about one of my matches. I have several gaps in my tree so most of my matches are unfamiliar. I've been searching through my matches to find similarities and mutual family members. One of my fourth cousin matches one of my moderate matches and it appears they have the same great great grandparents, which I think should make them third cousins. No other line in their tree appeared to match. I'm assuming since I match them both that I probably match on the same line, but what I don't understand is why one is a fourth cousin and the other is only a moderate match. By appearances, they should both be fourth cousins. Am I assuming wrong? Why else would it show up like this?