You are partly right about beans. Growing children need protein laden foods as their body is building up various systems (skeletal, respiratory, digestive, nervous, etc, ). The first use of such foods is to satisfy requirement for all round growth.
Coming to height, ensure that the kids indulge in activities that promote or stimulate "lengthening" of bones. This may sound weird. But see that they do a lot of swimming (after which they will be very hungry), bicycling with the seat slightly raised (legs will have to be stretched to paddle the bicycle), etc.
Think of activities that will keep them busy and out of doors.
Hope this helps. All the best