How can i verify two alike trees?

Question:

How can i verify two alike trees?

I have been researching my family tree for several years, and now I've hit about as far as I have been told I can go, but I'm not going to give up. I found a branch on "familysearch.org", and the person a)has the same name as my great great grandfather,
b) was born in the same area, and
c) has a birthdate that makes him old enough to be his father.

The only catch is, the information was collected a couple years before my grandpa was born, so it says they have no children. also*, in my dad's babybook, my grandpa had written "william" as the fathers name, and "sinclair" as the mothers maiden name, both of which do not match the ancestral file. what do you propose I do?
I was also suggested to by some friends that perhaps they had changed their names because of a crime, or for no aparent reason. they could also be uncles/aunts. But I really do hope it's his parents... what do you think?

Additional Details

8 months ago
Thanks for your help, but I have to add, that there are only 6 people left in my family, and I'm 17 and I'm the middle. the others don't know.

Best Answer - Chosen by Asker: 8 months ago
Thanks for your help, but I have to add, that there are only 6 people left in my family, and I'm 17 and I'm the middle. the others don't know.