Relations-thing, is eating me

OK, I have a problem., there are some stuff that seem so simple to some people but it is so freaking complicated to me. One of those things is the relatives' relations or so called the family tree, when it comes to these relations , my mind stops working, I feel that the crack in my mind is in the same exact region which is responsible for this skill , if it was a skill.

I noticed that in the funeral of my father's uncle (the brother of my grandmother) . when he died I discovered that this man was the uncle of my aunt's husband (my dad's brother -in-law ,also his cousin ) confusing huh?..I really don't know . Is that only in my family?..

so my little brother asked me what is the relation between my grandmother and my this person? o.k the answer was so clear that they are brother and sister LOL...just that easy, well it is easy now cause i found my way to you to make you understand.

so I looked at him and couldn't answer and if something that I really hate is not answering my little brother's questions so I told him keep this ques.,I will be right back.

and I went to the bedroom closed the door , brought a white sheet and a pen and I started to get all relations on paper, I found some interesting stuffs , *thank God my father and mother aren't related that was going to complicate everything*

then my paper was in my hand , found all I needed to tell him the exact answer.

OK fine I have problem when it comes to relations, I wonder why is it so blur to me?!