<p>Is what we choose important? I selected on my common app that I wish to major in Bioengineering, then Chinese language/culture, then Chemistry, when I applied SCEA to Stanford.</p>
<p>However, it doesn't seem like there is much to back up my interests in those fields, except in my essays. I'm interested in them and all, but it's more practical for me to study something else I'm more experienced with. Should it matter?</p>
<p>I think the only case in which it would matter is if you applied to some highly specialized major within a specific school. I know some schools have unique majors (History of Math at Amherst; Physics and Philosophy at Yale), so showing a particular interest in those may be taken into consideration, but I highly doubt it's worth warping your own interests to fit.
For what it's worth I'm indicating Biology and Theology as my intended majors on the common app, and have nothing else to back it up other than some some science courses and an essay touching on spirituality. They're not expecting you to have extensive background in these topics - thats why you're going to college! =]</p>