Why are babies so into stairs climbing or anywhere they see people can go up and down?

I don't think it's because the stairs attracts them, but mainly because they're huge copycats! Then they'd realized that views are different and it's fun to see the adults' reactions. This was what my daughter explained to our 6 year old neighbour after they saw her brother trying to get down a flight of stairs after being told not to. Having said that, do guide your child to put his feet down first before moving down the steps so that he wouldn't trip!