An informal fallacy where a claim is accepted or rejected based on the source of the evidence rather than on the quality of the evidence. The fallacy shifts focus onto the origin in an attempt to impugn or bolster the argument instead of analyzing the argument itself. This fallacy is similar to the ad hominem fallacy as both address either the messenger (ad hominem) or the source (genetic) in order to avoid evaluating the argument on its own merit.
Person 1 presents an argument where claim A is presented in support of the conclusion. The source of claim A is revealed in the process (e.g., expert authority figure, scientific journal, etc.).
Person 2 attacks the integrity of the source.
Therefore, A is false.
Person 1 presents an argument where claim A is presented in support of the conclusion. The source of claim A is revealed in the process.
Person 2 praises the integrity of the source.
Therefore, A is true.
The following abbreviations are used in the examples below:
PN = The Nth premise for N = 1,2,3,…. (e.g., P1 is the first premise, P2 is the second premise, etc.)
C = Conclusion
1) Often times, when I was in the grips of the GMO skepticism phase of my life, I would use the following argument, which I still encounter to this day:
P1: Look at the business practices and history of Monsanto as a chemical company. They harass farmers who they falsely accuse of patent infringement and they produced agent orange during the Vietnam war.
C: Therefore, I can't trust the safety surrounding GMOs with a company that behaves like that.
Explanation: The business practices of a company has nothing to do with the robustness of the science surrounding the safety of a product*. GMOs have been studied for decades and, at this point in time, there is a strong scientific consensus surrounding their safety . I am definitely committing the genetic fallacy here as I'm attacking Monsanto instead of addressing the science surrounding GMOs.
*Note, feel free to criticize the business practices of a company. One of the side effects of capitalism is that it puts profits above all else, which can lead to rapacious behavior that should not be tolerated by society. Furthermore, the product must be open to independent investigation. If the company is the one paying for the science, then there would be reason to doubt the results as bias would become a significant concern. That said, this is NOT the case for GMOs. They have been studied for decades across a myriad of regulatory bodies.
2) During the same time that I was in the grips of anti-GMO sentiments, I was concurrently concerned about the safety of vaccines (no surprise there). Fueled by my irrational fears, I also distrusted the regulatory bodies who were in charge of ensuring their safety. Consequently, one of the arguments that I used for vaccines and still encounter to this day went as follows:
P1: Look at the revolving door between the FDA/CDC and the corporations that they're supposed to regulate. In particular, the CDC and “big pharma” There's no way that this isn't seriously impacting the credibility of the safety studies.
C: As a result, the science surrounding vaccine-safety can't be trusted.
Explanation: While it is reasonable to question the ethics surrounding individuals who cycle employment between government regulatory bodies and industry positions for which they are supposed to be regulating, this doesn't automatically imply malfeasance. Furthermore, as with business practices surrounding GMOs, the hiring practices between government regulatory bodies and industry should be separated from the science. The veracity of the science must be evaluated on its own grounds. In this case, the science overwhelming supports vaccine safety to the point of a consensus .
3) This is an example from a Facebook discourse that I engaged in a few years ago that I will always remember for how outlandish the arguments made by the other interlocutor were. That said, the entire discourse surrounded global warming in which I was arguing on behalf of the consensus. At one point, after providing a link to the NASA website  on climate change, the other interlocutor retorts with:
P1: NASA is a Muslim agency (provides link to an article where President Barack Obama was traveling to a Muslim-majority country in the middle east and asked an individual who held some prominent position in NASA to aid in science outreach on his trip).
P2: How can NASA be trusted to be telling us the truth because they're helping Muslims?
C: Global warming isn't real.
Explanation: Candidly, I was flummoxed for a minute or two because I couldn't believe what I had just read. Not only is it a bigoted comment, but also very flawed. Instead of addressing all the science presented on the NASA website, the other interlocutor decided to directly attack NASA in an attempt to dismiss my argument. Overall, the discourse was infuriatingly illogical and depressing to watch another human degrade a civilian science organization with bigoted diatribes. Last, let us not forget that there is also a strong consensus surrounding global warming 
4) Throughout my tenure with complimentary and alternative medicine (CAM), I observed all sorts of arguments that implemented the genetic fallacy as individual's cognitive dissonance wrestled to justify their positions lack of credible scientific evidence. In general, there was a master argument that the CAM ethos embraced in order to justify its existence. The argument goes something like this:
P1: The medical system is broken here in the U.S. compared to other high-income nations *. While we have some of the best medicine in the world (i.e., surgeons, general care practitioners, emergency response time, etc.), when incorporating other metrics such as cost, access, equity, etc. we, in actuality, have one of the worst healthcare systems.
P2: The reason for this is that our medical system has become adulterated by capitalism and corrupted by the fiduciary obligation of corporations to maximize profits for their shareholders.
P3: CAM is being attacked by the medical establishment because they don't control it and it cuts into their profits.
C: Therefore, people should be skeptical of conventional medicine and avoid listening to their criticisms surrounding CAM.
Explanation: As I said before, business practices must be separated from the science. Feel free to castigate a corporation over their business practices – particularly if human lives are endangered or belittled in the pursuit of profits - however, you must not conflate the two. In this case, this is exactly what's happening. The argument mixes business practices with the science, which it then uses to not only denigrate conventional medical treatments, but to also justify dismissal of any criticism over CAM's lack of efficacy for the vast majority of its treatments (e.g., chiropractic, acupuncture, essential oils, etc.).
*Note, this is true. The U.S. does have one of the worst health care systems in the developed world, which deserves serious attention .
As is always the case, if you find yourself confronted with this fallacy in everyday discourse, it is important to remember that it renders the argument bad and should be rejected. What is more, if you find yourself using this fallacy within one of your own arguments, as an individual who ascribes to the philosophy of Critical Thinking, you must replace it with a good argument.