Alternative Hypothesis (and there are many): People of a lower-socioeconomic demographic both have greater chances of a poor upbringing as well as poor health as they get older.
Lot of confounding variables you need to correct for here.
"The 17,000 or so patients in this study were mostly middle-aged white people, upper- and middle-class, from San Diego."
It's true that there are a lot of variables when asking broad questions like what causes poor health, but it seems like the majority of the participants weren't of a lower-socioeconomic demographic, as indicated in the article.
It is "adjusted for age, gender, race, and educational attainment."
84% where white.
59% of Americans identify as middle class, upper-middle or upperclass. So saying that the study used mostly upper- and middle-class doesn't really tell us anything.
Ironically, the only link to the word "income" on that page was a related story-link, "People With Low Incomes Say They Pay A Price In Poor Health".
I remain unconvinced that "Family Secrets Make You Sick" based on that article. There are a lot of ways to determine whether that might be the case, but I'm surprised, based on the article's description, that they were able to get a paper published with their method.
Lot of confounding variables you need to correct for here.