Obviously, the cost to sequence a genome depends on its size. The discussion below is focused on the human genome; keep in mind that a single 'representative' copy of the human genome is ~3 billion bases in size, whereas a given person's actual (diploid) genome is ~6 billion bases in size.
Alternatively, EPA has a more beneficial effect on lowering overall LDL (bad) cholesterol. In the cognitive domain, DHA appears to offer greater mental benefits. DHA has been suggested to be more effective in improving overall cognition and preventing cognitive decline in healthy older adults.
Adults need to get DHA from food, and a baby in utero needs to get these fats from its mother. Newborns get DHA from breast milk or from baby formula supplemented with DHA. It's so important that even if a mother doesn't consume much DHA, her body will use its own reservoir of DHA to provide it to her growing baby during gestation and then through breast milk after birth.