Marines are part of the Dept of the Navy

I don't think the Marines would want anyone to serve with them who didn't want to be a Marine.

We always thought they looked like Army but then we would be reminded to think
of marine meaning wet ocean and then we would remember they were navy.

We would argue with our mother about it, we were sure she was wrong and the Marines were army.

They looked nothing like the sailors we saw all the time since they lived next to our AF base when
we stationed on a tiny South China Sea island during the VN war.

We saw the marines get on the LSTs headed for Viet Nam. I often think about those guys and hope
they all made it back home.

The Marines have a officer program run out of Quantico. Not sure of the details though.

People who obtained their college degrees somewhere other than the Academies, and want to train as officers. In the case of Quantico, the Marine Corps.

After graduating Annapolis an officer may select the option to go to the Marine Corps.

There is also a Marine ROTC program and a person can attempt to join directly as an officer if they have completed college.

Also is is possible for an enlisted Marine to apply for, or be offered, a spot in Officer Candidate School. Such an officer is referred to as a mustang.

I do not know what the percentages of each are but the Corps does have more that go the mustang route than other services.

He was slightly older than his fellow Second Lieutenants, but he brought with him the experience accrued as an enlisted man. To say that the tankers in our platoon adored him would be an understatement.

As you saw, their experience was invaluable when they became leaders.

I am proud to have had three of my Marines make the jump over the years. Twice I was offered the chance but decided to keep my stripes. I knew I wouldn't have advanced past company grade.

But will get to field grade. I've known a Colonel and a few LTCs that started as enlisted.

For myself, it was a combination of my age and the politics to move up the officer ranks. I knew I would only get to Capitan, Major at best.

November 10th. I always acknowledge my USMC friends on that date. One day before veterans day.
They were born of the US Navy.

The Marine Corps does not have an academy. Naval Academy usually choose either the Navy or Marine Corp but they could go into the Army, Airforce or become a Space Cadet....

To answer your question more specifically, most of the officers in any of the service branches to not attend the service academies. However, an Academy ring nearly assures rapid promotion and good assignments. It is a fraternity that looks after its own, and many times regardless of the fitness or ability of the graduate.

of the Air Force like the Marines are part of the Navy?

But I would say they are part of the Dept of the Air Force, not the Air Force service branch….

There are six armed service branches

There is the U.S. Army that falls under the Dept of the Army
There is the U.S. Air Force and U.S Space Force that fall under the Dept of the Air Force
There is the U.S. Navy and U.S Marine Corp that fall under the Dept of the Navy
The three aforementioned Departments fall under the Dept of Defense

Then there is the U.S. Coast Guard that falls under the Dept of Homeland Security