Genetically modified food is one example of artificially manipulating the normal DNA molecule of a particular species. It's caused pollenating bees to die and the same thing with birds who eat the seeds. You can imagine what it does to people over time. Genetic modification can take place over time in the form of micro-evolution in that animals and peoples adapt to their surroundings in relation to climate and food. This might not be a direct answer to your question, but it may be how familial tendencies are acquired.