The answer is yes, so your brother's experience is completely to be expected!

Yes. Theoretically, 50% of seedlings will be either male or female.

If you look at them, while in bloom, you can differentiate the genders - male flowers come in groups of 3, females are singles.

Thanks for the answers. I tried a cleft graft with Oriental persimmon on it last year that did not take.

Wisner

Find out the sex of the tree then graft a male or a female branch as needed.

Tony

I do not know these native persimmon(American Persimmon, not Japanese) grow wild in my woods, so I never needed to know.

Thanks to everyone who answered for me.