While Millennials have been shifting the landscape with their unique spending habits, they tend to shift to reflect older generations' after they settle down and start families, according to a study by Goldman Sachs. Younger Millennials' shopping priorities are still natural and organic foods with transparent labeling, but those who have children and spouses tend to to look for value, convenience and selection like previous generations did, reported Bloomberg.

Of course, even if the data holds out when the younger cohorts of the Millennial generation start settling down, there is still plenty of time for them to permanently change how retail grocers work. Millennials are less likely to get married and live on their own than any previous generation. While 56% of 18- to 31-year-olds were married and living in their own homes in 1968, that number dropped to 43% in 1981, 27% in 2007 and 23% in 2012, according to Goldman Sachs. The median age of marriage in the 2010s is 30, compared to 23 in the 1970s.

They're also putting children off longer, though 74% of Millennials still want to have them at some point. The most common age for women having children in the 2000s and 2010s is 30, compared to 25 for previous decades.