Is germline genetic enhancement better than somatic genetic enhancement?

The various types of human genetic modifications can be divided along two lines – the therapy-enhancement divide and the somatic-germline divide. The former refers to whether a modification is therapeutic or enhances and the latter refers to whether a modification is affects children (by affecting reproductive cells or whole embryos) or just affects the body (without affecting reproductive cells).

We are therefore left with four categories (Resnik 2000):

1. Somatic gene therapy (SGT)
2. Germline gene therapy (GLGT)
3. Somatic genetic enhancement (SGE)
4. Germline genetic enhancement (GLGE)

What I want to explore is whether, in a world where adults can opt to be genetically enhanced, there would ever be any benefit to germline genetic enhancement. That is, can we avoid all the ethical issues with germline engineering and genetically enhance only consenting adults?

I think there are three general reasons why it might be beneficial to genetically modify the germline, rather than waiting until people are old enough to consent. (However, note that some of these benefits might be achieved by somatic engineering in infancy, which would essentially create a ‘designer baby’ while leaving the germline untouched. This wouldn’t side-step any ethical issues around consent so I’m ignoring this possibility)

1. GLGE could be in the child’s best interests

The vast majority of enhancements people would seek in adulthood would also be things people would want their children to have as they grow up. It is likely also that children themselves would choose (if they were legally able to consent) to go through school with improved intelligence, to play with better reflexes or to be physically attractive while experiencing the first teenage romance. And that’s not mentioning things like resistance to disease or faster wound healing that exist on the cusp of the therapy-enhancement divide.

2. GLGE may be technically superior to SGE

Some modifications may be technically difficult to achieve in an already developed body consisting of billions of cells, and may prove much easier when only single celled gamete or zygote is modified. It might be difficult to get the DNA to every cell that needs to be modified, and some modifications might, at least initially, only prove possible if the genes are edited before the body’s organs and systems develop.

However, it’s quite possible that an enhancement which was only possible with germline methods would 18 years later could be achieved – or even surpassed – by somatic methods. In this case, if you imagine persons could give consent at age 18 for somatic gene enhancement, then any advantages of GLGE over SGE would only be temporary ones during childhood and at the age of consent everyone would be on an equal playing field again.

A fast pace of biotechnological progress would also mean that inherited germline enhancements might be little benefit to future generations compared to somatic enhancements that exist by that time. If a mobile phone could survive over generations, you’d still not pass it down to your children because it would be hopelessly outdated. So barring major disasters that set humanity back into a dystopia with little technology, passing your enhancements on to your children would only be a benefit if germline enhancements remain far superior to somatic enhancements over that time.

3. GLGE can affect motivations

Though a person choosing a somatic enhancement will choose based on their wants, the effects of a germline enhancement can directly affect what it is that a person will want (once they are old enough to choose). To paraphrase German philosopher Arthur Schopenhauer: “Man can choose to do what he wants but he cannot choose what it is that he wills”. I should point out that genes cannot control everything, but they can have some affect on the future choices a person will make.

This means that narrow-focus enhancements which are desired by only a few, or even undesirable to anyone who could choose, may be only be possible by way of modifying the germline (or somatic modifications in children). Portrayals of germline enhancement in science fiction often involve armies of soldiers or slaves engineered from conception or childhood to not only excel at their designated role but also to enjoy being perfectly obedient. These portrayals often involve growth rate enhancements to get around the reality that such such soldiers or slaves would take decades to ‘manufacture’. In practice, anyone with the power, resources and decades worth of time to commission and care for their own soldiers or slaves would either be ethically prepared to use somatic techniques to modify the desires of adults or be otherwise be able to pay/bribe adults to do the same job.

Because people sometimes make choices they regret or that aren’t in their best interests, there may be benefits to altering a person’s motivations. It may be reasonable to desire that your children make ethically good and smart choices once they become adults. So, if any germline enhancements can improve logical reasoning and moral motivations, children gifted with such enhancements will be in a better place to make wise choices, including when selecting which somatic enhancements they pursue as adults.

Conclusion

I think there are some very good practical reasons to pursue genetic enhancement of the germline and of children. There may still be ethical reasons to oppose it, but I think the potential gains are large enough some at least will feel it ethically acceptable (or ethically right) to pursue germline genetic enhancement even in a world where somatic genetic enhancement was possible. If parents are pursuing enhancements out of love, they may be prepared to do ethically questionable things to achieve what they believe is best for their children.