My dad had flat feet and was worried that the NAVY wouldn't take him in WWII. They took him. Sailors don't march too much.
I didn't get his feet. I'm always having to even double up on insoles to have enough arch support.
Suction on a wet deck, built in swim fins... no wonder the Navy okayed flat feet. Nothing disparaging your dad (and thank him, if he is still around, for me) but the navy in WWII was taking lots of folks they wouldn't during the post Vietnam force reductions.