Every bit of information helps a teacher including what home life is like. I found out that half of my class lives with one parent and the other is in prison. That will impact a child's learning greatly.
Though I'm sure it would help you, if it's something they really don't want you to know and you have the ability to know all their childhood trauma just by touching them, isn't that a bit invasive and unfair? They have a right to not have someone know something unless they want them to.
People are entitled to have control over their own life, their own bodies, their own trauma and which people know what. It's a very personal thing.
Especially if they already have trauma, this will be a huge violation of their privacy and their feelings of control. If someone did something you wouldn't morally approve of, surely they have the right to keep that to themselves instead of conforming to your values to avoid judgment? That's the whole idea behind Don't Ask Don't Tell.