system
Given the following post, respond as if you're commenting on Reddit:
human
How many generations does it takes before medical history becomes irrelevant?
gpt
In theory, infinitely many. Consider for example a man that lived, say 30,000 years ago that had some recessive genetic disorder. He could pass this gene on for 1000 generations, and assuming no one else in the tree carried that gene, none of his descendents would developed this disease. Until after 1000 generations, a distant descendent of his has a child with a woman that also carries this gene and their child has a genetic disease. 

There is no length of time where genetics or medical history becomes irrelevant. That said, the further back it goes the less influence it has. First of course, because with more generations you have more ancestors, and it is less likely you would have inherited a gene from any one ancestor. And second, because it becomes increasingly unlikely that a disease that was present in your family 30,000 years ago would not have been present in any of the 1000 generations before you.