I didn’t actively think about this. It just popped into my head one day and after I looked into it I was pleasantly surprised.
If my wife and I have one more child, making our newest son, Xander, the middle child. He will then be (at least) the 5th generation of the male middle child going back to his great-great-grandfather.
I have only traced my ZALEWSKI line back to Frank Zalewski, but I only know of one of his siblings and nothing about the rest of his family. It is completely possible that he is also a middle child, but I don’t know, yet.
Frank’s son Joseph was the 5th child out of nine, born in 1893, making him the middle child. Frank’s 3rd child, Elsa, died within a year, so Joseph didn’t really grow up a true middle child.
Joseph and his wife Emily technically had four children, though one died stillborn, making three living children. Joseph’s son Richard was then the middle child, born in 1921.
My father, Richard’s son, was born a middle child between his brother and sister.
I was born a middle child surrounded by two brothers.
There are always neat things hiding in your family tree if you look for it.