A person's type of happiness can affect their genes

[muriel_volestrangler]

11. This seems to say it affects how the genes are expressed

not the genes that you pass on to your children.

From the paper:

Previous studies have found that circulating immune cells show a systematic shift in basal gene expression profiles during extended periods of stress, threat, or uncertainty. This conserved transcriptional response to adversity (CTRA) is characterized by increased expression of genes involved in inflammation and decreased expression of genes involved in type I IFN antiviral responses. The CTRA transcriptional program likely evolved to help the immune system counter the changing patterns of microbial threat ancestrally associated with changing socioenvironmental conditions (e.g., increased risk of wound-related bacterial infection associated with experienced threat or social conflict vs. increased risk of socially mediated viral infection associated with affine social contact). However, in the very different environment of contemporary human society, chronic CTRA activation by social or symbolic threats may promote inflammation mediated cardiovascular, neurodegenerative, and neoplastic diseases and impair host resistance to viral infections. The present analysis used the CTRA gene expression profile as a high-dimensional molecular reference space in which to map the potentially distinct biological effects of hedonic and eudaimonic well-being.

www.unc.edu/peplab/publications/Fredrickson%202013%20PNAS.pdf

So I think this is saying that stress can make your immune system emphasise defence against wound infection, at the expense of other parts of your health; and that can also happen to 'hedonic' people, although they regard themselves as happy, not stressed.