Monday, January 19, 2026
One of the questions we occasionally receive is whether ducklings hatched and shipped together could be brothers and sisters, and whether that could cause issues for customers interested in breeding down the road. It’s a smart question, especially for people who care about the long-term health and productivity of their flock.
To understand the answer, it helps to first understand what inbreeding actually is.
To understand the answer, it helps to first understand what inbreeding actually is.
What Is Inbreeding, Really?
Inbreeding is defined as the mating of closely related individuals, such as full siblings or parents to offspring. In poultry breeding, this practice is sometimes used intentionally by experienced breeders to “fix” specific traits, like egg production, conformation, or temperament. When done carefully and with strict selection, inbreeding has historically been used to develop many successful commercial and heritage poultry strains.
That said, inbreeding becomes risky when it is practiced too closely for too long, within very small, closed populations or if it is not closely monitored. In those situations, undesirable recessive traits can become concentrated, leading to issues like reduced hatchability, lower fertility, slower growth, or decreased overall vigor.
Why Flock Size matters
The key factor here is flock size. The general rule in the genetics world is that you need at least 75 female birds and the matching males in a flock that randomly mate to prevent inbreeding.
In small backyard flocks, especially those made up of only a handful of birds, there will be inbreeding if you keep a small number of females and males and only keep their offspring. If you only have two females and one male, for example, it might take three to four inbred generations before you see bad traits. If you have ten females and three males, however, it will probably take four to six generations to see any sort of deleterious effects of inbreeding. It is a complete numbers game.
It also matters how inbred your original birds were. If they came from completely different breeding lines from breeders emphasizing different characteristics, you might require 50% more generations to see bad traits due to inbreeding.
If your flock has several completely different breeds, you could probably double the number of generations before you see signs of inbreeding.
Commercial hatchery breeding operates very differently.
At Metzer Farms, our breeding flocks are intentionally large and genetically diverse. Large populations naturally reduce the chance that any two birds are closely related in a way that would negatively impact offspring. Even when birds share distant ancestors, the genetic variation within a large flock prevents the concentration of harmful recessive traits that cause problems. And with larger flocks you have a greater chance of a spontaneous mutations that also prevents inbreeding. Simply put, the larger the breeding population, the lower the genetic risk.
Are Ducklings From the Same Hatch Closely Related?
While it is biologically possible that some ducklings from the same hatch could be closely related, the likelihood that they are closely related in a way that would negatively affect future breeding is extremely low. Though we strive to have similar appearing birds that match APA standards, we have multiple flocks ourselves. Due to Avian Influenza concerns, we do not want all our breeders in one location. In fact, we try to have two different breeder flocks for each breed in Tennessee and the same in California making a total of four flocks for each breed we have. In addition, the research shows that many negative effects blamed on inbreeding are more often caused by poor nutrition, inadequate management, disease, or lack of proper selection rather than genetics alone.
What This Means for Breeders
Many breeders choose to introduce new birds over time to add even more diversity, which is a common and effective long-term practice. If you are breeding on a small scale, paying attention to flock size, rotating breeders, and selecting strong, healthy birds will do far more for your success than worrying about whether two ducklings from the same hatch might be distantly related.
The Bottom Line
Inbreeding is not inherently bad, but it is a tool that must be used intentionally and carefully. In large hatchery breeding programs, flock size and management practices naturally minimize the inbreeding risks that concern backyard breeders. Customers can feel confident that birds from our hatches are bred with long-term health, productivity, and genetic diversity in mind. If you ever have questions about breeding, genetics, or building a sustainable flock, we’re always happy to help. Raising ducks should feel exciting, not intimidating.