When I was young, I never got gassy, regardless of what I was eating and how much I was eating.

But at one time I was forced to take antibiotics orally for a rather long time.

After that, eating anything like beans resulted in copious amounts of gas, so it was obvious that the composition of the bacteria community in my guts had been changed.

After many years, the reactions to beans and the like have diminished, but I have never reverted to the condition from before that exposure to antibiotics.