Human Genetic Improvement
by Paul
VanRaden
© 1985
Quotes
from leading thinkers 1693-1983
Proposal for Human Progeny
Testing
Introduction
People differ
in their abilities to be happy and in their abilities to lead productive and
useful lives. People differ in part because they have been raised in different
environments and in part because they have inherited different genes. Despite
their differences, all people could probably agree that new babies should
receive genes which would lead them to be productive, useful, and happy rather
than genes that would cause them grief, if only this were possible. In an
abstract sense, then, every reasonable person should be in favor of genetic
selection in humans if it could be used to cause his own children to grow up
happier while at the same time causing no detrimental effects to anyone else.
For many
people, though, the mention of genetic selection in humans brings to mind an
image from a few decades ago of a terrible breakdown of society and a very evil
dictator making the selections. It is unfortunate that such an event occurred.
But people who value freedom should realize that, if given the chance, genetic
selection could just as easily be associated with freedom and kindness as with
dictatorship and evil.
Individuals
now are for the most part limited to giving their children their own genes,
whether they are happy with those genes or not. A better system is needed, one
that allows individuals who realize they have not inherited the best genes in
the world a chance to do something about it. Someone whose own genes have
caused him grief might consider it the highest form of morality and of
unselfishness to want his children to have the best genes possible, or at least
to have genes free of defect, rather than to have his own genes if in fact
these are the source of grief.
A purpose of
this paper is to argue in favor of giving people the information and the means
necessary to make decisions regarding which genes their children will inherit.
This could be accomplished by determining which sources of genes actually do
cause productiveness, usefulness, and happiness and then by allowing people to
choose such genes for their children if they desire.
They could
also choose to contribute their own genes, as currently, but for people already
unhappy with their genes, the thought of contributing these genes to their
children might make them even more unhappy. Practical questions then involve
how one measures happiness and how one separates genetic from environmental
factors. These questions will be addressed.
The Proposal
The purpose of
this paper is to present a program to facilitate genetic selection in humans.
Specifically, the topic is how to give people who would rather pass genes other
than their own on to their children the means to identify and to obtain the
kind of genes which would cause their children to be happy. Formerly, one's
only choices were to have or to not have children. It is good that new choices
are now becoming available.
Artificial
insemination (AI) in humans is already being done on a wide scale in the U. S.,
with about 20,000 babies being born by this technique each year (Anderson,
1982). This is generally not for couples who have voluntarily decided to give
their children genes from someone else but for couples in which the husband is
infertile and they have no other choice, save adoption. But whether the choice
is voluntary or involuntary, it is difficult to argue that those who use AI
would rather give their children genes which they know little about as opposed
to genes the effects of which they have studied. Therefore, even if the
prospect of couples voluntarily choosing outside genes is ignored, the large
number of infertile couples who now resort to AI makes the topic of genetic
selection an important one, especially important to those directly involved in
raising these children and of course to the future children themselves.
To understand
how one might choose a source of genes which would cause one's children to be
happy, some background information and genetic theory is needed. A simple
method for choosing sources of genes is to rank individuals based on their own
measurable traits (phenotypes) and then to choose those that seem most
desirable. This is the idea behind the "Nobel sperm bank", which was
started in 1980 to provide a source of superior genes for those who want them
(Saladin, 1980) and also is the method advocated by Muller (1961).
Unfortunately, as has been the case in many animal species, such selection
often chooses individuals whose environmental circumstances are very favorable
but whose genetic makeup may be much closer to the population average than one
would hope.
In animal
populations, a very simple method is employed to solve this problem. It is the
progeny testing of males. For many traits, determining the value of an
individual's genes by looking only at that individual's phenotype is difficult.
This is because a large proportion of the differences between individuals may
be due to environmental or unexplained factors rather than due to genetic
differences. The proportion of variance between individuals likely to be of
genetic origin is called heritability or h**2. The heritability to which this
paper will refer is the narrow sense heritability, which measures only the
amount of genetic variance which parents pass on to their children in a
hypothetical random-mating population.
Progeny
testing allows the genetic merit of an individual to be estimated precisely,
the precision being a function of number of offspring and heritability. By
evaluating a large number of offspring of many males, those males whose progeny
seem most desirable in some sense can be selected to produce additional
offspring. The same principle could be applied to females, but at this time
females cannot contribute their genes to large numbers of offspring nearly as
easily as males can. In the future, embryo transfer may alleviate this problem
to some degree.
One of the
important principles in progeny testing is randomization of usage. This
distributes the progeny of gene sources evenly and fairly across a population
so that differences in average merit of progeny reflect only genetic
differences of the males tested and not differences in the environments their
progeny were raised in or differences in the merit of females who contributed
their genes and mothered these progeny. Randomization also ensures that progeny
will be raised in a wide variety of environments so that results can be
generalized to the population at large.
Objections
People may
raise several major objections about the idea of human progeny testing and
genetic evaluation. The first objection is one already discussed in the
introduction. In most people's minds, the idea of genetic selection in humans
is directly associated with the phenomenon of Hitler. Thus, it is wise to see
if there are any differences between the ideas of Hitler and those proposed
here.
In the current
proposal, no individual can force any other individual to reproduce or not
reproduce, no one can force another to use their own genes or to use someone
else's genes, ideally all children are born to parents who want them, and the
government need not and even should not get involved in the process. Genetic
selection is controlled by parents deciding to contribute either their own
genes or someone else's genes to their children, and if they choose someone
else's genes they have the right to use any or all information in deciding
whose genes might give their children the largest chance of being happy. Or,
they can obtain genes from a random, unevaluated member of the population as is
essentially what those who use AI now are forced to do.
A second
objection is that the heritabilities of important
human traits may be too small and the generation interval may be too long to
make genetic selection in humans worthwhile. A counter-argument is that the
distress caused to those who inherit genes causing poor health, poor looks, or
poor brains is so great that any improvement in their condition is worth the
small trouble it takes to achieve it. Realistically, the progress to be gained
by genetic selection is not enormous, but then neither is the cost. Surely, if
selection programs for animals can yield positive returns on investment,
selection in humans should have much higher profitability.
A third
objection is that closely related individuals might unknowingly marry each
other if large numbers of half sibs are created. This situation would not occur
often but could easily be avoided if children conceived by AI were told this
fact and were also told some identification number of their genetic father.
This identification could be in coded form to prevent a child from actually
discovering his genetic father if this were desired. Snowden et al (1983) have
studied children conceived by AI and recommend that these children be informed
of this fact rather than to keep their genetic origins a secret.
Two related
objections are that having a large number of offspring from a single male is
too risky in terms of genetic defects and that such a program might result in a
substantial reduction of genetic variation and inbreeding. The second of these
objections is put to rest very easily when one considers that the number of
males contributing genes to the next generation would still be huge even with a
very successful AI program. The first objection appears to make sense only when
the progeny of a particular male are grouped artificially by themselves. But
when one considers the risk to any couple conceiving a child by AI, the risk of
genetic defect is no greater than, and in fact is bound to be less than, the
risk for a child obtained naturally. This is because those males known to be
carriers of genetic defects would be eliminated as donors. When one considers
the population as a whole, the average number of genetic defects would also
decrease.
Although
overall genetic disease rate should decline, incidences of a few rare diseases
could happen to increase due to chance heavy usage of some heterozygous
individuals. Nevertheless, a big benefit of progeny testing is that it would
aid in the process of carrier detection (VanVleck, 1979). Individuals would
have many more relatives, so that a larger proportion of suspected carriers
could be informed of this fact and greater strides could be made in reducing
genetic disease.
A final
objection is that the whole idea of genetic improvement of humans is somehow
unnatural or immoral, or is playing God. People who feel this way certainly
have the right to continue to give birth to children by natural means. But if
the option was readily available, many couples might rather play God by giving
their children genes from a well-tested source than play roulette by giving
their children genes which they know little about, or worse yet, genes which
they know to be harmful.
Reasons for Progeny Testing
There are
three simple, straightforward reasons for initiating a program of progeny
testing and genetic evaluation in humans. They are a) that those couples who
cannot or do not wish to pass their own genes to their children will finally
have a reliably tested source of genes available for substitution, b) that
important questions regarding how much of the variation between individuals is
of a genetic origin may finally be answered, and c) that even those couples who
continue to reproduce naturally will have a better understanding of what traits
they may or may not pass on to their children as a result of information gained
in this study.
A final reason
for starting such a program is that similar programs with domestic animals, for
instance, dairy cattle, have been very successful and economically rewarding.
It always seemed wrong to me as I grew up that I and my fellow farmers could
spend such time and effort searching for the right genes to put into our next
generation of crops and livestock, and yet when it came time for us to
contribute genes to the next generation of people, each person was expected to
contribute his own genes to his child unthinkingly, whether or not he was happy
with those genes himself and whether or not he knew that there were better
genes easily available. It didn't make sense then, and still doesn't.
Practical Problems to Overcome
Several
problems must be overcome if large-scale progeny testing is to become a
reality. Sufficient numbers of couples must be found among those coming to AI
clinics who will agree to be part of a progeny-test study. This means they must
agree to have data collected from their child throughout the child's early
life, say until the age of 18. Data collection even after this age would be
desirable, but then would be subject to consent of the child. Couples who wish
to keep their involvement with AI a secret may not wish to cooperate with data
collection. However, with the recommendation now that children be informed of
their genetic origins (Snowden et al,1983), agreement for data collection may
be easier to obtain.
If
progeny-test results are to be reliable and believable, randomization of donor
to couple must be done. Ideally, one would like usage of all donors to be
completely random, but couples are not likely to agree to this. Some grouping
would have to be done and then donors chosen randomly from within the group.
Grouping could be on race and on certain visible body characteristics, for
instance.
Currently,
donors are matched to couples based on resemblance of the donor to the husband.
If randomization within groups is used, matching of donors to husbands could
not be done quite as accurately. Nevertheless, if couples do not intend to keep
AI a secret, it is probably less critical to have the child look like the
husband.
A big problem
might be just to decide what traits or how many traits to measure on the
resulting offspring. General categories of traits to measure might include
physical characteristics, abnormalities, athletic ability, looks, intelligence,
personality, and interests, but one could think of hundreds of ways to measure
such traits and there would be many individual components within each trait.
Much research is needed to determine which traits are important and how to best
measure them. Obviously, the more traits that are measured, the more
information is gained, but also the more unwilling that couples would be to
have their children subject to such detailed scrutiny.
A sufficient
number of long term semen donors would need to be secured. Agreement to supply
semen for, say, 40 or 50 initial progeny for the test would not be sufficient.
The idea is that, once progeny-test results are available, semen from the top
ranking males would be in large demand. Thus, it would make sense for all males
in the progeny test to continue banking semen in frozen storage during this
waiting time. Finding males to agree to provide semen over many years should
not be difficult, however, if they are allowed to profit from their efforts. It
is not difficult to imagine progeny-tested human males earning $100,000 or more
per year from semen sales alone. Progeny-tested bulls can earn much more than
this and their progeny are only cows, not people.
For the best
progeny-tested males to really have an impact, much more efficient usage of
semen is required. Problems to overcome in this area are timing the
insemination to coincide with ovulation and placing the semen in the uterus or
cervix rather than the vagina. Research on both of these topics is progressing.
Ovulation can now be detected by chemical, temperature, or ultrasound methods
and intrauterine insemination can usually be carried out without complication
although success rates are still low as compared with animal species.
Some national
system of identification of donors would be needed so that progeny of AI could
verify, when they married, that they were in fact not marrying a half sib by
chance. Such potential marriages would be rare even if large groups of paternal
half sibs existed, because the children of one male would likely be distributed
over the entire country and would constitute only a very small proportion of
the total population. Nevertheless, for peace of mind of those involved, it
would be good to compare identification of genetic fathers. Perhaps something
simple like social security number of donor would work without making it too
easy for children to contact the donor if he did not wish to be contacted.
Collection of
data itself could be a difficult task. One might want to obtain peer
evaluations for a trait such as "niceness" or
"easy-to-get-along-with-ness" for instance, but such information
would be difficult to obtain without singling the child out or making the child
feel awkward. School records and results from certain standardized tests could
be used, but this might require contacting a different school for each child in
the study, which could be expensive. Keeping track of addresses for couples and
their children would also require some effort.
Analysis of
the data should not be a problem if randomization is carried out properly.
Statistical procedures for ranking sires are already well developed from animal
data. Unfortunately, much precision is gained in animal data by having progeny
of several of the sires to be evaluated all raised together in a common
environment, such as a herd. This would be difficult to do in humans, but in
its place certain variables on the parents such as education and income could
be collected to correct for environmental differences somewhat.
Implementation of the Program
Starting a
national or even regional program of human progeny testing and genetic
evaluation would require much coordination of effort. Nevertheless, since
similar programs are already operating profitably in animal populations, the
task cannot be that great. One might think that a single national program
carried out under the guidelines of a governmental or independent agency would
be most effective. A government program probably also has largest chance of
being abused. An alternative would be for competing private firms to design
their own programs. Obviously, competing firms could still agree to coordinate
their data collection and data analysis efforts. The competition would then
focus on which firm could most efficiently find and deliver the kind of genes
people would like their children to have.
AI clinics are
already in place and doing substantial business. What is required is to
organize the usage of particular males in such a way that their genetic merits
for various traits can be accurately determined. This would require finding
couples who agree not only to use the particular males of the study as donors,
which should not be difficult, but to allow data collection on the resulting
children. For couples to give prior agreement, they would probably want to know
exactly what sorts of data will be collected and they might also want the
option of allowing some variables to be collected while refusing others.
Funding for
data collection could be a problem unless only already-recorded variables such
as school grades or results of standard tests are to be used as traits of the
study. Traits which require a researcher to visit each child would be somewhat
more expensive to measure, but these traits include some of the most
interesting and some which have never been studied before, such as a most
important trait, looks. Data collection expenses could be charged against later
revenues from sales of semen. This would require only some venture capital.
Example of Intended Results
Suppose, for
example, that 100 males are progeny tested initially and that they obtain an
average of 50 progeny each. After approximately 18 years, assuming that data
are collected on all progeny, a summary could be produced which might look
something like Tables 1 and 2.
Table
1. Gene sources ranked on overall index.
Estimated
Transmitting Abilities1 |
|
Gene sources: 4816 |
|
|
Overall
Index2 |
129 |
126 |
124 |
|
Looks |
+1.31 |
+.83 |
+.58 |
|
Intelligence |
+.20 |
+1.19 |
+1.91 |
|
Athletic
Ability |
+1.50 |
-.35 |
+.35 |
|
Peer
Evaluation |
+.44 |
+.72 |
-.09 |
|
Childhood
Happiness |
-.26 |
+.22 |
+.19 |
|
Artistic
Ability |
+.00 |
+.05 |
-.96 |
1 Expected differences
of this source's progeny from the average source's progeny. All traits except
overall index have standard deviation of 2.
2 Computed as 100 +
10*(looks + intelligence + peer evaluation + .7*athletic ability + .4*childhood
happiness + .3*artistic ability)
Table
2. Additional traits of gene sources.
|
|
Gene sources 4816 |
|
|
Eye
color alleles |
brown, brown |
blue, blue |
brown, green |
|
Hair
color alleles |
black, brown |
brown, blonde |
brown, red |
|
RH
factor |
+ + |
+ - |
+ + |
|
ABO
blood type |
o, o |
A, o |
o, o |
|
Height
(inches) |
+.74 |
+.28 |
-2.11 |
|
Weight
(lbs) |
-5.3 |
+2.5 |
-8.1 |
|
Ease
of birth (s.d. = 2) |
+.61 |
-.10 |
+.94 |
|
Price1 |
$30,000 |
$22,000 |
$21,000 |
1 Price per pregnancy in
U. S. dollars. If no pregnancy occurs after 10 inseminations, 1/2 payment is
refunded and agreement cancelled. Prices also available for per- insemination
service.
This is just
one approach for presenting the results. Many people might not wish to be
confronted with such detailed information about the sources of genes available
to them. Nevertheless, the purpose of the tables is to stimulate discussion
about what traits are important to human happiness and how sources of genes
which contribute happiness might be selected and distributed.
It may appear
that the weights in the index for ranking gene sources are somewhat arbitrary.
This is, of course, true. Each person might have his own feelings about which
traits should be included in the index and what their relative emphasis should
be. Nevertheless, an overall index can be designed to reflect the average
person's views and is just an aid for condensing the many numbers which might
appear for each gene source down into one useful number. Anyone whose views
differ substantially from those of this overall index would be encouraged to
construct their own index and rank gene sources on it.
The overall
index should include those traits for which the optimum is in one direction and
which most people would agree are important. Other traits exist with
intermediate optima, for instance weight, which individuals on either end of
the distribution might be concerned about but which, on the average, the
population may not wish to change. Traits which are expressed earlier in life
could be given higher emphasis relative to those not expressed for many years
because inexpensive non-genetic solutions may be found to cure problems caused
by genes, for instance, plastic surgery to correct problems of appearance.
The prices in
Table 2 are, of course, pure guesses. Still, it is reasonable that couples
might regard that giving their child a proper set of genes is about of the same
value as giving the child a college education. The quantity of semen available
from the best gene sources will greatly influence price. It might be that 100
children per year could result from each male, but if this figure is too high
or too low, prices would be affected inversely. In other species, for instance
cattle, the best males now sire many more than 10,000 progeny per year but such
rates are not likely with humans for some time.
Many people
might, upon seeing the prices in Table 2, complain that the program would
benefit the rich and do nothing for the poor, whose children could benefit most
from having an improved sample of genes. Table 2, however, reflects only the
uppermost prices, which there would be few of. Semen from most of the remaining
males would be available at much more reasonable prices, and semen from males
evaluated to be below average probably would be discarded. Anyone who could
afford to raise children could probably also afford AI.
Conclusions
A program of
progeny testing and genetic evaluation should be initiated in humans, because
it would be profitable, because it would answer important questions about the
inheritance of many traits, and because it would provide a source of reliably
tested genetic material to those concerned about what genes they pass on to
their children. In a democratic nation which stresses individual freedoms and
an abundance of choices, such a program could provide a large amount of
happiness with little chance of abuse. It would give to parents the option of
not having to pass poor genes on to one's children if one was not so happy with
those genes himself.
This program
would not need, and would not tolerate, a dictator or some mad scientists
deciding who should reproduce or what genes should be reproduced. Rather, it
would require only that parents consider, when creating a new child, whether
that child would be happiest with their genes or with the genes of someone
else, and if someone else, who that someone should be. A voluntary program like
this would be hard to abuse in a society where individual consent is required
for almost every decision, and obviously consent would continue to be required
for such a personal decision regarding reproduction. Besides, laws prohibiting
the natural production of children would be very hard to enforce, even for the
most dedicated police state.
A more likely
possibility for abuse comes from those who would, through legislation, force
others to accept their own ideas that babies should always have their parents
genes rather than having the best genes possible, or force them to accept that
random selection of donors is preferable to actually finding out which donors
have the best chance to donate happiness.
Artificial
insemination with donor semen is already a common phenomenon, with many
thousands of babies conceived in this way each year. It would be nice to think
that the parents of these children, and indeed all parents, would be concerned
enough about their children's futures to at least wonder whether the genes
their children receive will cause them to be happy or sad. It is time to begin
questioning some traditional ideas about reproduction and to begin demanding
more information about how the genes we give our children affect their
abilities to lead happy lives. Genetic selection is not an entirely new
concept, but it is surely a concept worth a second evaluation.
References
Anderson, J.
K. 1982. Genetic engineering. Zondervan Corp., Grand Rapids, MI.
Muller, H.J.
1961. Human evolution by voluntary choice of germ plasm. Science 134:643.
Saladin, K. S.
1980. The Nobel sperm bank: an affront to humanism. Humanist 40:61.
Snowden, R.,
G. D. Mitchell, and E. M. Snowden. 1983. Artificial reproduction: a social
investigation. George Allen and Unwin, London.
VanVleck, L.
D. 1979. Notes on the theory and application of selection principles for the
genetic improvement of animals. Dept. of Animal Sci., Cornell University,
Ithaca, NY.
"Proposal
for Human Progeny Testing" was written in Ames, Iowa in 1985 while I was a
graduate student studying animal breeding.
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