1. Gain of function research primarily uses samples collected from nature, and seeks to stimulate their evolution in as natural a way as possible to learn how viruses evolve in nature. If such viruses were to escape the lab, they would appear "natural"
2. It's not xenophobic for people from the US to suggest the possibility of a lab leak, because the US was itself funding gain of function research on novel coronaviruses in the Wuhan BSL4 lab
3. Lab leaks happen more often than most people realize[1]
[1]https://www.vox.com/future-perfect/2019/3/20/18260669/deadly...
There is, from my understanding, reasonable evidence to conclude the virus was not engineered from the perspective of "we took genes from one virus and moved them to this virus," but there's no evidence disproving the idea that it was the result of gain of function research.
My personal feeling is that these statements are true:
* The virus is unlikely to have been engineered (in the way I described above) and leaked.
* There is circumstantial evidence the virus was the result of gain of function research and it leaked.
* There is circumstantial evidence the virus was a natural research sample and it leaked.
* There is circumstantial evidence the virus was introduced by an animal/person who traveled to the wet market.
Some of these are more likely than others, and an individual's own calibration for what is likely or unlikely will probably come into play more than evidence in the short term and possibly long term as well. I can say the vast majority of us are not qualified to answer the question either way though.
It's also worth noting that even the leading experts can get these things wrong, as was the case with the Sverdlovsk lab leak.
Soviet authorities covered it up by blaming local meat markets, and leading US experts concurred with them, only to reverse their conclusion 6 years later.
https://en.m.wikipedia.org/wiki/Sverdlovsk_anthrax_leak#Acci...
Which will always look suspicious, whether it was actually a completely natural virus or not.
Wouldn't the Wuhan lab be able to disprove this really easily? How often do they sequence viruses? Couldn't they show categorically that COVID-19 is not a descendant of a virus they were working with/on?
It is not feasible to do this probably. The WIV even claims to have completely consumed all biosamples related to RaTG13, which is the most-closely-related known virus to SARS-CoV-2. Supporting such an investigation is completely counter to their interests (speaking both of the institute and the CCP).
The overwhelming evidence is that SARS-CoV-2 emerged completely adapted to humans. This has been confirmed by the amazing lack of initial adaptation to the new human host. We only saw major changes in the spike resulting in a change in phenotype later in 2020. The proximal origins of the spike protein suggest a primate or human host. For this to happen, a natural origin in another species is astronomically improbable. It's the strongest evidence that we'll ever have as to the origins of the virus, and to this biologist it is completely indicative of what happened. We will only know the full truth if people speak out.