The actual thing that those companies like 23andme get is your consent. Your genes already stick on everything you touch. They are basically public. If you ref

The actual thing that those companies like 23andme get is your consent. Your genes already stick on everything you touch. They are basically public. If you refund something bought at an online retailer, they could theoretically use the opportunity to sequence your genes. But they don't because they need your consent. But then again, genes are just biological manifestation of data and in your TOS you agree to them processing your data and using it to recommend products to you don't you? If most people don't care how many data companies collect about them, will they care if the online retailer is doing something like this?