It's normal for ANY intelligent person to realize nutrition had an effect on height, not just liberals.
There is no denying that politics does play a role in the size of one's pants though; here's the proof:
http://calorielab.com/news/2010/06/28/fattest-states-2010/
Yes. It is also true. Genetics is only a predisposition, but a person needs the proper nutrition to reach the height they are genetically predisposed to achieve.
If you take two twins, feed one well and feed the other barely enough to survive, the well-fed one will be slightly taller than the malnourished one since his or her body will have had more building blocks to work with.