Sentence:  ... I witness firsthand the difficult "downstream" outcomes (Grusky 2014) of social class stratification in a university setting where approximately 3,400 undergraduates (13% of the undergraduate population) are first in their families to attend and/or graduate from college (first-<WSD>gens</WSD>). Most of these students are low income and nearly 1,200 first-<WSD>gens</WSD> have grown up in poverty. 
Meaning of the word marked with <WSD> tags:  A specific version of something in a chronological sequence.