What age you will allow your kids to go up stairs??

I let mine start doing it as soon as they were able to try (they were crawling, but not walking so less than one year). The reason being, I wanted them to learn how to do it safely so that if they ever did end up on the stairs without my knowing it, they would already know how to handle it. I did stay right with them while they were learning, obviously! The tricky part is going down. They figure out going up pretty quickly. But they need to be shown how to *back* down, rather than trying to go facing the direction they're trying to go. I taught them this by letting them get to the top of the stairs on their own, with me right behind them, and then while they stayed in the same position, would start moving them slowly down the stairs until they got the idea. I think that if there are stairs in the house it is much safer to teach them how to navigate them than to try to keep them away from them.