Im the 4th child in a set of 5. There also is 17 years between the oldest - who will be 40 jan 21, and the youngest - who will be 24 a week before her.
We all have severely different personalities, my sister was a freshman in college when I started 1st grade. Even now I'm not so close with my 3 older siblings. Granted we get along just fine, if an outsider were to threaten any of us 5 the other 4 would help handle it (be it boyfriends, legal, money whatever) Maybe it's just because I lack perspective or real life experience comapared to their respective ages of 40, 38 & 33 to my 26. It wasn't until my middle brother and ! both were in college and we had some common ground - probably because I grew up from being a dorky high school know it all. Im closest with my younger brother, there are 3 and 3/4 years between us. Of all my siblings, if I had to pick a roommate, it would be him. I will say tho, My nieces who are now 15 and 14, We can get together & have a great day like were all old friends. Not so easy with my sister or their father.