It is definately O.K. to house a male and female together. I use Rabbit pellets "rabbit food" as substrate for my hatchlings and yearlings. (If they eat it, no harm) I used bermuda hay for my little ones, and they just burried them selves and slept for days. with the rabbit pellets, they go exploring and get much more excersize. For my torts one year and older I use bermuda hay, they pack it down by walking on it, dig a few burrows, and munch on it when they get hungry. As far as breading brother and sisters..... I dont know! Can anyone else help us with this one? I need to know because my largest male and female may have come from the same parents, and If it makes a difference I will seperate them.