system
Given the following post, respond as if you're commenting on Reddit:
human
Does your DNA alter throughout your lifetime?

Does everything you come in contact with in your life alter your DNA chemistry in any way? All of your experiences? All of your emotions? Physical damage? Healthy or poor eating? Hygiene?


UPDATE: All of this is amazing you guys. I appreciate all of the effort you all put in to explaining. It’s truly amazing; the human body.
gpt
By and large your cells are doing their level best to prevent your day to day experiences from having any impact on your DNA. Just about all chemicals you ingest/inhale from whatever sources (food stuffs, drugs, smoke, oxygen, bacteria) will have some impact on your cell's DNA. Plus some other sources of damage such as ionising radiation like UV light or skin contact of chemicals. 

Any time any foreign chemicals can get to your DNA they have the potential of reacting with it and causing changes (damage). Because this is an ever present and continuous risk your cells contain a whole suite of repair systems that detect any damage and put things back as they were. But these systems are not perfect so over your lifetime your cells will pick up random changes just from your day to day exposure to your environment.

 This is also the cause/basis of most cancer, if you're unlucky some cell(s) in your body will end up with the right pattern of damage to send the cell cancerous. In large part the DNA repair systems are there to prevent this happening.

All that being said there are some legitimate changes to you genes that happen in your lifetime. Our immune system has a cassette of genes used to generate antibodies. In our antibody producing cells this cassette of genes is randomised and this allows us to produce cells with near infinite variations of possible antibodies.

Alongside this we also have epigenetic changes. These aren't changes to the DNA sequence,  instead these are tags that can be added to genes to control how they are expressed. This pattern of tags is available to be edited during your lifetime and it does respond to environmental stresses. One good example,  starvation has been shown to have a marked epigenetic impact on people's genes and it has been shown mother's will pass on their epigenetic markers to their kids.