How is your life expectancy due to both genes and the environment?

Life expectancy is affected by both genes and environment because; 1) one could have genetic underlying health issues that could cause an untimely demise, and 2) the environment in which they live could have uncontrollable events which may shorten one's life, such as violence, limited access to health care, and pollution.

genetic variation can be caused by mutation (which can create entirely new alleles in a population), random mating, random fertilization, and recombination between homologous chromosomes during meiosis (which reshuffles alleles within an organism's offspring).