Neither you nor I have consented to the genes we inherited. Our general makeup was dictated to us by our ancestors. I had no say in my allergies, my short stature, my baldness, my tone deafness, nor in my even my general temperamental bent. I have accepted all these traits as a given. As has every generation before me. But we will have more choice about this inheritence in the future. At some point we might clench our fists and rail against the gods for our genetic lot — as I am sure I would do if I had a serious genetic disability — and do something about it.  Everyone has inherited at least one fatal genetic disease we all share — it’s called Old Age Death.

The vast majority of the genes in me, are in a very serious sense, not mine. They were given to me, and I will give them to my children and their children. And taken as a whole most of “my” genes are shared with all humans. Only a tiny tiny fraction may be different. Essentially my genes are a shared asset.  So what I do with my genes is not just about me. This is where genetic engineering gets interesting.

There are three levels of genetic engineering of humans:

1. Altering an adult
2. Altering an embryo
3. Altering the germline

Each of these interventions should be treated slightly different.

1) Altering an adult is currently difficult to do, although it is being tried in different ways to treat inheritable diseases. The idea is to alter or replace areas of DNA that cause problems in an individual. The practical hurdles include delivery of the new DNA to the cells, getting the change to stick, and the fact that most diseases are caused by more than one gene.  The most successful delivery system so far discovered it to use modified viruses to “infect” a patient with the altered DNA. The complications of virus delivery are easy to envision. Our bodies are very good at detecting and resisting outside “not my body” stuff, including not-my-DNA, so even if we can change the genes of some working adult cells, getting the change to stick is difficult. Lastly, being able to modify many genes in different parts of the sequence at the same time is a big challenge. So far altering the genes of an adult is uncommon. However if it could be made to work well, easily, it would be the preferred way to alter genes. First the adult would give consent, and it would only affect them (assuming it was not a reproductive change), and the consequences need only be evaluated for one life.

2) Altering the embryo is easier to do, but has its own challenges. We might think that the embryo has not consented to the changes, which is true; but it has not consented to any of the other genes it is inheriting either. From its perspective, any genes it gets, come without consent. It did not choose its ancestors or parents. The challenge is the complexity of genes, and the fact that there are no free lunches, no gains without side effects.  The issue is our ignorance as parents and ancestors.

Let’s say I make up a list of all the traits I would like to give my children: Super smart, able to run a marathon, no fear of heights, risk taking, extrovert, compassionate, photographic memory, empathetic, tall, thin, sonorous voice, easy going, no allergies, comfortable with math, good listener. Who would not want all these in their children?

But traits are not items that we can simply check off from a shopping list and download into the organism. They don’t work that way. Yes, it is possible to insert a list of genes, but that does not mean you’ll get a list of traits. Most traits are not generated by a single gene, but rather complex of genes. More importantly, even single gene traits are modified, offset, altered, or displaced by the action of other genes. A trait emerges from an ecosystem of genes, all interacting upon each other.

The challenge is the human proteins needed to make each of these to happen can conflict with each other. The proteins — created by the genes — needed for risk taking may be the ones that dampen good listening. There are genetic trade offs, in that you cannot optimize all traits. In other words there are genetic costs for each trait. To raise IQ might cost lowering something else, such as empathy. It’s not that there is a zerosum quantity being conserved, it’s that genes cannot do all that is possible. They are constrained by each other. It is like trying to design a machine: it cannot optimize all properties; it cannot be fastest, lightest, strongest, and cheapest at the same time. Everything is a trade off. Performance, reliability, speed, cost — all are trade off between them.

The dream of designer babies will wither within the first couple of generations of people trying it. Once the side-effect traits are revealed in practice, the emotional burden on the parents becomes a natural inhibitor. Parents will be faced with the fact that they deliberately engineered these traits into their child.  They chose to add the undesirable trait. They may have even accepted the downsides as the price for the upside. In natural inheritance, it’s harder for a parent to beat themselves up for genes they have no control over.  And a child, too, my carry resentment for a parent’s decision about their genes. This heavy pyschological role may relegate designer babies to removing diseases that anyone would be glad to rid. But even this alteration can have undesireable side-effects, which will become part of the agonizing calculus.

3) Altering the germline has the same conundrums as altering an embryo, but amplified many orders of magnitude. Ideally we would want to have many decades of experience in somatic gene therapy (altering one body) first before messing with all generations. Perhaps this is where regulation might come in. We want to have a clear idea of what side effects and downsides an alteration may have by seeing what happens in the body. Then we can let it flow in the line. So we might have a societal mechanism were proposed gene changes are approved or prohibited.

However this is a line of societal control that would be new to us. Right now, we allow all kinds of undesirable genes to proliferate in the human gene line through natural reproduction. We make no attempt to prevent people with the gene for X from having children. Such interference is seen as an affront. But if we began regulating synthetic genes in the human germ line, there would be an incentive to regulate genes from natural procreation as well.  Indeed it is easy to imagine that a society-wide resistance to engineering the human germ line is not due to the potential genetic changes that might come about, but to the societal control that it would entail. People would not resist designer babies; they would resist the intrusive social control required to manage breeding designer babies.  This reluctance could significantly delay and slow down germline genetic engineering.  There may in fact be societies in parts of the world that prohibit gene editing for this reason; to avoid any kind of genetic oversight.  This could be a natural inhibition to eugenics.