(Identical twins are close to a natural experiment but not a very good one as even they don't have the same genetics.)
If you have to limit it to "humans only", the claim falls apart anyways, because genetics isn't human-specific
Simply put, you haven't made a convincing case that genetics, a science affecting all life, not just humans, is "not a credible science", despite indeed involving experiments all the time.
Below is where you can make that case.
This is a far stronger claim than I think you mean. We have a ton of evidence that those bits of DNA in our cells govern cell expression and even know in some cases that bit X being malformed causes bad condition Y (sure, you could hypothesize that they both have a common cause, but how the heck would that work? Correlation being causation works if both common cause and backwards causation are implausible, as they are often in genetics).
> but not a very good one as even they don't have the same genetics
Uhhh... they have almost exactly the same genetics. To a similar extent that two random cells from your body will have the same genetics. Yes, there will be a handful of mutations, but that's very unlikely to have an effect on any particular trait.
DNA just encodes proteins. It can’t explain/predict detailed behavioral patterns. A prominent example of how genetics can influence aggressive/criminal behavior is due to variations in the MAOA (“Warrior”) gene, but the promotion/suppression of this gene is still strongly influenced by environmental factors [1].
Twin studies (particularly separated twin studies) claim to prove that all kinds of things are genetically encoded, because “they must be”, without considering how much is caused/influenced by other factors - the gestational environment and the experience of being separated from the birth family being the most obvious.
[1] https://www.ncbi.nlm.nih.gov/pmc/articles/PMC3469457/#:~:tex....
(Also, did you check out the paper I linked?)
I’m fine to have a discussion if your intention is to achieve a shared understanding of the topic, which is what healthy debating is about and what this site seeks to cultivate (even if it rarely achieves it). It does seem a little like you’re more interested in “winning” an argument for a position you’re already invested in, but I’m happy to be shown otherwise and to engage in a discussion if you bring a spirit of shared learning to it.
Edit: rather than doing it here (in a thread that is already very long and stale) you can email me if you like (address in bio).
Here's a random study on criminality I was looking at a bit ago: https://www.sakkyndig.com/psykologi/artvit/frisell2010.pdf