The main kinds of genetic test, what each is for, and roughly what it costs, so you can tell which one your question actually needs.
For most people, most of the time, a basic targeted DNA test is enough, and whole genome sequencing is more than you need. Whole genome sequencing reads almost your entire genetic code, which sounds appealing, but more data is not automatically more useful, and it comes with real costs in money, complexity, and sometimes anxiety. The right choice depends on why you are testing, not on which option sounds the most thorough.
Partly, and with real limits. A nutrigenomic test reads genes that influence how your body handles certain nutrients, which can offer useful clues about things like caffeine sensitivity, lactose tolerance, or how you process fats. What it cannot do is hand you a complete, guaranteed 'perfect diet.' It gives you a few well-evidenced signals and a great deal of marketing dressed up as more than it is.
Partly, yes. A specific kind of genetic test called pharmacogenomic testing can tell you how your body is likely to process certain medications, which can help a doctor choose a drug or a dose more accurately. It does not cover every medicine, it does not guarantee a drug will work, and it never replaces your doctor's judgement.
The main types are wellness and lifestyle tests, clinical disease panels, carrier and reproductive screening, pharmacogenomic (medication-response) tests, and ancestry tests, each built for a different purpose.
A wellness test tells you how your body tends to handle nutrition, fitness, sleep, stress, and caffeine, useful, low-stakes information for everyday choices, not a diagnosis.
No. Consumer DNA tests estimate risk and report tendencies; they do not diagnose. A flagged risk should always be confirmed with a proper clinical test before anyone acts on it medically.
Carrier screening checks whether you carry a hidden recessive variant, like thalassemia, that is harmless to you but matters if your partner carries the same one, because a child could then inherit the condition.