The Punnett Square

Via calculates inheritance odds: as a carrier, she has a one-in-two chance of passing the defective gene to any child. If she marries a carrier, her children have a one-in-four chance of being unaffected, one-in-two of being carriers, and one-in-four of having a condition like August’s. If her partner is not a carrier, none would be affected, though some could carry the gene.

Via then considers August’s potential children. With a non-carrier partner, all offspring would inherit the gene but none would have a double dose, so they would look typical. If August’s partner is a carrier, their children face the same one-in-four risk of being affected. She notes that part of August’s condition stems from non-inherited, unlucky factors beyond these odds.

Recalling years of medical consultations, Via describes doctors using Punnett squares to explain probabilities and terms like “germline mosaicism,” “chromosome rearrangement,” and “delayed mutation” to admit uncertainty. She finds solace in the sound of scientific language while recognizing its limits, ending with a stark reflection on the many unborn possibilities it implies, including the children she fears she might never have.