Basic Genetic Principles for Couples
Every person carries a unique set of genetic instructions inherited from their parents. These instructions shape much of who we are — from eye color to height to certain aspects of our health. For most couples, genetics work quietly in the background. But when planning a family, understanding a few basic principles can help you make informed decisions and prepare for the future with confidence.
You do not need a science background to grasp these ideas. The core concepts are straightforward, and learning them empowers you to ask good questions, understand testing options, and appreciate why certain screenings are recommended before or during pregnancy.
This article offers a clear, accessible introduction to genetics for couples, along with guidance on the halachic questions that often arise. Our advisors at PUAH can help you navigate every step of this journey.
What Are Genes and Chromosomes?
Inside nearly every cell in your body is a complete set of genetic instructions. These instructions are written in DNA, a chemical code that tells your body how to grow, function, and repair itself.
DNA is organized into structures called chromosomes. Most people have 46 chromosomes, arranged in 23 pairs. You inherit one chromosome of each pair from your mother and one from your father. This is why children resemble both parents.
Along each chromosome are smaller units called genes. Each gene carries the instructions for a specific trait or function. Because chromosomes come in pairs, you typically have two copies of each gene — one from each parent.
How Traits Are Passed Down
When the two copies of a gene differ, one may be dominant and the other recessive. A dominant gene shows its effect even if only one copy is present. A recessive gene shows its effect only when both copies match.
This distinction matters greatly when discussing inherited conditions, as you will see below.
Understanding Genetic Carriers
A carrier is a healthy person who carries one copy of a gene linked to a recessive condition, but does not have the condition themselves. Carriers usually feel completely well and have no symptoms.
The situation becomes important when two carriers of the same condition have children together. In that case:
There is a 25% chance the child will inherit two copies and have the condition.
There is a 50% chance the child will be a healthy carrier, like the parents.
There is a 25% chance the child will not have nor carry the disease.
If only one parent is a carrier, the children cannot develop the recessive condition, though some may become carriers themselves. This is why testing both partners is so meaningful.
Why Genetic Screening Matters
Genetic screening identifies whether you and your partner carry genes for the same recessive conditions. Because carriers have no symptoms, the only way to know is through testing.
Certain genetic conditions appear more frequently in specific populations. Within Jewish communities, several recessive conditions are more common, which is why carrier screening is widely recommended before marriage or before pregnancy.
When to Consider Screening
Screening is most useful before a couple becomes serious or before pregnancy, when the most options are available. Many couples choose to be screened during the dating or engagement period. Others test early in pregnancy.
The earlier you have this information, the more time you have to consult with medical and rabbinic experts and plan thoughtfully.
Types of Genetic Testing
There are several kinds of genetic tests, each serving a different purpose:
Carrier screening — checks healthy adults to see if they carry recessive genes that could affect their children.
Prenatal testing — examines a developing pregnancy for certain conditions.
Preimplantation genetic testing (PGT) — used during fertility treatment to examine embryos before pregnancy begins.
Each option carries its own medical considerations and halachic implications. Choosing the right path depends on your specific situation, and this is precisely where guidance becomes valuable.
Halachic Perspective
The rapid advance of genetic science has created what may be described as a revolution in how we approach family health. With this revolution come profound halachic questions that Torah authorities have addressed with great care.
From a halachic standpoint, the overwhelming majority of contemporary poskim permit carrier screening, and PUAH's own rabbinic leadership actively encourages couples to undergo it. Couples can therefore approach this process with confidence, knowing that seeking this information is not only permitted but strongly supported by leading halachic authorities.
Halachic considerations touch many parts of this topic. They include questions about when and how to undergo carrier screening, how to handle results, the permissibility and proper use of preimplantation genetic testing, and sensitive decisions that may arise during pregnancy. The Torah places great value on health, family, and human dignity, and these values guide the halachic approach.
Importantly, genetic information is best handled with discretion and wisdom. The way results are shared — and with whom — often involves halachic and personal sensitivities. PUAH's team of doctors and rabbis specializes in exactly these situations, helping couples receive and respond to genetic information in a manner that is both medically sound and halachically appropriate.
Specific questions should be discussed with a qualified rabbinic authority. Our team at PUAH is available to help you navigate these questions.
When to Speak With a Professional
You may want to consider speaking with a professional if:
You are planning to marry or are early in a relationship and have not yet been screened.
You and your partner discover you are carriers of the same condition.
There is a known genetic condition in either family.
You are considering or undergoing fertility treatment and want to understand testing options.
You have received genetic test results and are unsure how to interpret or act on them.
In any of these situations, you do not have to face the decisions alone. Reach out to PUAH. Our advisors combine medical knowledge with halachic expertise to support you with clarity and care.
Summary
Genes and chromosomes carry the instructions we inherit from our parents, and understanding carriers and recessive conditions helps couples prepare wisely for family life. Carrier screening, especially before pregnancy, offers valuable information and time to plan. From a halachic perspective, the overwhelming majority of poskim — including PUAH's own rabbinic leadership — actively encourage couples to pursue carrier screening. Both the medical and halachic dimensions deserve careful attention, and PUAH is here to guide you through both.
Disclaimer: This article is intended for educational purposes only and should not replace medical advice from a qualified healthcare professional. Personal halachic questions should be discussed with a qualified rabbinic authority.