Although I'm not in Texas but to be honest, there's too many gray areas, regardless of location.
I'm only going to speak to you, parent to parent.
As a parent of 4 & 6 years old (both girls), I do shelter my children (i.e. private school). I let them be themselves the way children should be without the negative environments such as verbal and sexual contents.
Unfortunately, I know of waaaaaay too many children, even at tender ages, they're not as sheltered. In other words, they know more about sex than they should be. Not to mention that curiosity is all too common in children.
IMHO, if my children were boy and girl, I would not allow them to sleep in the same room without supervision. It's for two simple reasons: 1) Curiosity can get them into trouble based on peer pressure and 2) I'd do whatever I can to avoid any potential trouble such as someone calling the Child and Family Service.
Like I said----too many gray areas. So the best you can do is to use your common sense and hope for the best.