I wouldn't do anything. Your job is to teach, not to discipline. Your students can choose to do or not do whatever work you set them; it's their education and their choice. Ultimately cheating only affects them and their learning.
Also, seconding the fact that if you give people a graded take home exam that implies open book (including the internet and each other)
Forensic data on you is already pretty easy to obtain unless you're taking special effort to avoid it being taken. Also when you get arrested they take whatever biometrics they like. The info on you those DNA testing companies are getting is info already easily available to the government. I guess if you're concerned about your DNA being used to tailor ads to you, not just to criminalise you, it could be an issue, but idk I don't think your DNA can really predict what ads will be effective on you.