SONGLyrical DNA
Fate Written in the Lab
A song about a couple who hope not to pass on an inherited condition, and the designer future their choices point toward. The lyrics run from family history, carriers and inheritance patterns, through in vitro fertilization, embryo testing and the difference between selecting embryos and editing DNA, to polygenic traits, pleiotropy, consent and genetic diversity. Select any highlighted line to see the biology behind it.
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Interactive lyrics
Lines with a dotted underline and a + marker have an explanation. Select one and the science appears beside the lyrics. Everything else is ordinary lyric text.
Verse 1
She said, "I want our baby chasing all the things they wanna do,
With more days feeling good than the days I've struggled through."
She folds the paper, takes his hand; they step into the day,
Same two people, same big dream, a little more to weigh.
He says, "Let's learn the options, take it one step at a time,"
She looks at him and smiles; the dream is still alive.
Still want those tiny footsteps, still want those bedtime songs,
Got another call to make; they bring their questions along.
Chorus
A little less hurt, a little more hope, (MORE HOPE)
Verse 2
Back at the clinic,
He writes down the next steps, puts a circle round the date.
She says, "I want our baby growing up without this terrible condition,
More time to chase their dreams and all the joy that life can bring."
More days out making memories, more time just feeling right?"
Chorus
Designer babies, fate written in the lab, (LOOK AHEAD)
Embryos selected, or genes we dream to transform. (ONE DAY)
A little less hurt, a little more hope, (MORE HOPE)
Genetic engineering, changing D-N-A, (CHANGE THE CODE)
Could we change a gene to keep disease away? (ONE DAY)
If our kids inherit edits, who gets a say? (WHO DECIDES)
Verse 3
Years roll on, she's scrolling through the clinic's shopping page:
What's a person if every person is just a click and a fee?
Are they buying their kid's future, or just buying their own dream?
At school, a kid says, "My designer genes cost more,"
Now the price tag from the clinic's walking through the classroom door.
"We came to stop an illness; how'd we end up buying it all?"
Final Chorus
Designer babies, fate written in the lab, (LOOK AHEAD)
Embryos selected, or genes we dream to transform. (ONE DAY)
A little less hurt, a little more hope, (MORE HOPE)
Genetic engineering, changing D-N-A, (CHANGE THE CODE)
Could we change a gene to keep disease away? (ONE DAY)
If our kids inherit edits, who gets a say? (WHO DECIDES)
Concepts covered
Family history and genetic testingA family history drawn as a pedigree shows which relatives were affected, across which generations and in which sexes, and that pattern hints at how a condition is inherited. Genetic testing then looks for the change behind the condition in this family, often by sequencing the relevant genes and comparing them with a reference. When a change is found, it usually becomes the target for later testing of relatives, or of embryos.
Carriers and recessive allelesEach person has two copies of most genes, one on each chromosome of a homologous pair. A carrier is heterozygous: one allele works and one carries the change. For many recessive conditions the working copy makes enough functional protein, so the carrier's phenotype, the observable trait, is unaffected. In an autosomal recessive condition, for example, a child is affected only after inheriting a changed allele from each parent.
Inheritance patternsHow a condition passes depends on its inheritance pattern. An autosomal dominant condition can appear with a single changed allele from one parent. An X-linked recessive condition shows up more often in XY children, who have only one X chromosome and no second copy to mask it. Knowing the pattern and the parents' genotypes lets a clinic estimate each child's chance of inheriting the change, and pedigrees help show which pattern applies.
Genotype and environmentGenes do not write a script that runs unchanged. A phenotype comes from a genotype interacting with its environment, and the same genotype can produce different outcomes under different conditions. Phenylketonuria is a clear case: people with two changed copies of one gene break down phenylalanine, an amino acid in protein-rich foods, poorly or not at all, yet a low-phenylalanine diet started in infancy largely prevents the brain damage.
Selecting versus editingEmbryo selection and gene editing work at different levels. Selection compares embryos that already exist and chooses one; it does not change any embryo's DNA. Editing would rewrite the nucleotide sequence inside a cell. Selection can therefore only choose among allele combinations the parents' gametes actually produced, while editing could, in principle, create a sequence neither parent carries.
Gene editing and inheritanceGenetic engineering changes DNA directly. Tools such as CRISPR-Cas9, a guide RNA paired with a DNA-cutting enzyme, cut at a chosen site, and the cell's repair can change the sequence, though not always as intended. Edits to somatic (body) cells, like blood stem cells edited in an approved sickle cell therapy to switch fetal hemoglobin back on, stay with that patient. Germline edits could pass to future generations and have not been shown safe.
Testing embryos for a known changePreimplantation genetic testing for a monogenic (single-gene) condition, or PGT-M, takes a few cells from the outer layer of an early embryo, the layer that forms the placenta. That tiny amount of DNA is amplified, for example by PCR (polymerase chain reaction), then checked for the family's specific change. The result covers that one condition only, it is not perfect, and a transferred embryo may still not implant.
Every embryo is a new combinationIn in vitro fertilization (IVF), each egg and sperm is a haploid gamete made by meiosis. Crossing over and the random assortment of homologous pairs give every gamete a different mix of a parent's alleles, and fertilization joins two sets into a diploid embryo. Rounds can fall short when few eggs are collected or fertilize, when embryos stop developing, often after nondisjunction, or when every embryo tested is affected.
Risks beyond the known changeA clean family history does not rule a condition out: recessive alleles can pass silently through carriers, new mutations arise in gametes, and many common diseases are polygenic. Testing an embryo for one known change says nothing about those other risks. Polygenic scores rank relative risk roughly, and lowering a risk never guarantees a condition won't occur. In 2025 the American Society for Reproductive Medicine found polygenic embryo screening not ready for clinical use.
Polygenic traits and a menuHeight and face shape are polygenic: many genes each add a small effect, so the traits vary continuously instead of falling into a few neat classes. Eye color depends mostly on a few genes with large effects, plus many with small ones. Height also depends on nutrition and health during growth, and faces keep changing with development and age. No test available today can predict or set these traits in an embryo.
Family resemblance and pleiotropyGrandma's nose can reappear because her alleles pass through a parent, who may not show the feature, and then combine again in a grandchild. Facial shape is built during development by many genes, and many of them also act in other tissues. That is pleiotropy: one gene affecting several traits. Changing such a gene to erase one feature could alter other tissues where that gene acts.
Consent and accessAn embryo's alleles are copied into every cell it develops into, so a choice made at the embryo stage stays with that person for life, and it is made before the person exists to agree. A child may come to value the very family features that were selected away. Cost adds a second issue: if only some families could pay, chosen alleles would be spread unevenly through a population, tracking wealth rather than health.
Genetic diversity in a populationA population's genetic variation is the range of alleles its members carry. If many families chose the same alleles for looks, those alleles could become more common and some visible variation could shrink, though many genes and the environment would keep faces from matching exactly. Variation is the raw material natural selection acts on, helping populations cope with new diseases and environments.
