How to allow zooming for touch devices?

I have a website (http://www.hairtransplantasia.com/), which is made in bootstrap. I tested it a lot while I was making it using the Mozilla responsive view feature and it was working just fine and was beginning to resemble a wire frame of what I wanted it to look like. Then I tried uploading it to. After that i saw in mobile, but the my HTC Desire 626 don't allow zooming, then i tried my friends mobile it was working just fine. I also used