One of the biggest impacts on upward mobility is personal relationships and examples.
with the way we draw up ward boundaries even poor youth are going to have a lot of contact with successful people. Having a lay leadership helps as well. Let's face it the leadership in Bishoprics and Young Mens are usually really successful people. Relationships are built with the youth. The Youth see their examples, hear their advice, and learn about their academic and career options from them. Through Scouting and Young Mens the world is opened up to them in unique ways. All of this is called cultural capital. These things are more unique to our church based on our lay leadership and ward boundaries.
Some examples
-I grew up in an affluent ward chalk full of scientists. Although my dad was an incredible scientist as well I will never forget many of the academic, science, or career related lessons from my bishop and youth leaders. Often times my leaders would take us somewhere, to a river or something, and we would discuss the science of that place and then it would somehow be tied to a spiritual lesson
-a few weeks ago our ward had a career or education night geared to the YM/YW. While it probably wasn't as effective as it could have been at least the youth learned that there are expectations to provide for your family and there are many pathways and options to accomplish that.