true, that makes sense ... I'm not a gene or biology specialist, but if you change the gene of a human and he has kids, the kids will inherit the modification, right? so my problem with all these gene manipulations is that the more we do and the more it will impact future generations and who knows what the impact on those will be? So for me having the adult consent is not enough as the impact is not just on him but potentially much greater.

Gene manipulation of an adult likely would target a subset of overall tissue. Although, ethics of modifying reproductive tissue could be an issue.

The difference is what happens if the edit in an adult is unsuccessful. I don’t think people are objecting to edits that are net benefits as much as preforming highly risky procedures.

Though like most ethical issues people don’t have universal objections.

If you modify bone marrow specifically, it won't be passed on.

When do babies consent to being born?

they dont!

it's not about consent. Or, even better, consent is a very weak argument. If you use the consent argument, then you need to apply it for other areas, like being against vaccines for example. But you probably don't use it there because you know that babies can't consent anything (or maybe you do, if you are an antivax).

The very brief discussion about it in genome.gov even mentioned that.