Perhaps it depends on the genetics? I'm not too sure how dwarf tomatoes were first started but I'm sure a lot of them were hybridized at one time or another to create a shorter, stockier plant. Just like people do cats and dogs. I guess if you grow multiple plants of a dwarf variety, save seed only from the shorter of the plants if there are any. I was told that Hannah's Prize reaches between 18-24 inches in height but on the Victory Seed website I saw a picture of a plant that looked taller than that.
When I looked up Bradley tomato under the forums database, I saw pics of the plants that looked like trees. Bradley is a short type.
