Well, I think both male and female feet could remain ticklish their entire life..
I tickled so many times my great-aunt feet: I slightly touch the sole, and she begins to giggle and move sayin' "no please".
Also my grandpa feet were so ticklish! I once tortured him with a feather for 2-3 minutes, he laughed so hard and it was difficult to hold his feet still!
PS: she was 80 and he was 83 😀
-----------------------------------------I'm 44 and my feet are as ticklish now as they have ever been 🙂