How do lifestyle and genetics determine longevity?

Both important: If your family lived a long, healthy life you have a good chance of doing so as well. However, if your lifestyle includes things like smoking, drinking too much, obesity and stress, the benefit of having good genes could be eliminated. The opposite is try too. A healthy lifestyle can help offset poor genes.

Both important but..: Both genetics & lifestyle are important factors in longevity but we are learning that lifestyle plays the larger role.This is because lifestyle affects genetic expression via epigenetics.We have 2 copies of each gene. Often one is more functional than the other & lifestyle (including mental attitude) affects which copy of the gene is expressed more. So genes influence but don't determine our fate!