Most box turtles can be sexed by eye colors. Males have red eyes, and females have yellow or brown eyes. But, sometimes females have red eyes too. Males have concave plastrons (their bottom shell is shaped like a bowl) while females' plastrons are pretty flat. Box turtles may be more apt to breed if they are hibernated. There are risks with hibernation. If it's not done right, the turtles can die. If you do it outside (in a fully fenced enclosure), it usually works. It's harder to do in a refrigerator.
My page on box turtles is at
http://www.fishpondinfo.com/turtles/box.htmI suggest visiting some of the box turtle links that are on my site as there's not much useful on my site about box turtles.