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.
In fact, the EFSA Scientific Panel recommends that pregnant and nursing women should consume an additional 100-200 mg DHA daily in addition to the 250 mg omega-3 intake recommended by EFSA for adults.