Browsers Zoom In and Out while Scrolling

Every time I open a page in either Chrome, Opera or Firefox and try to scroll with the tip of my finger, the browser seems to suddenly zoom in and out while scrolling, interpreting the scroll down as a pinch AND scroll gesture. This is f****** annoying. This problem does not occur at all on Android's built-in browser, so I must advise this is not a problem with my touch screen. I experience this issue on my LG Optimus L3, with Android 4.1.2 Jelly Bean. ***EDIT 1***: The problem is probably inherent to the cell phone model, as only I and a friend, who owns an identical phone, have this same problem. ***EDIT 2***: The problem seems to be solved for the last Google Chrome update, but Opera unfortunately still behaves in this way. This means that it isn't a user interaction problem, but a bug.