Updated September 26, 2026. This page used to answer its own question with “cluck yes!” and then explain, two lines later, that chickens have Z and W chromosomes instead. The real answer is no. I’ve rewritten it to say so plainly, and to show why that one fact explains sex-link chicks, wing-feather sexing and why no egg trick can tell you a chick’s sex.
The short answer: no. Chickens, like all birds, have Z and W sex chromosomes, not X and Y. A hen is ZW and a rooster is ZZ. It’s the reverse of us, so in chickens it’s the mother, not the father, who decides whether each chick is a pullet or a cockerel.
Z and W, in one paragraph
The University of Kentucky puts it simply: “In birds, however, the sex chromosomes are referred to as Z and W, with females having ZW chromosomes and males having ZZ.” So it’s the hen who decides. Every chick gets a Z from its father, because a rooster has nothing else to give. From its mother it gets either her Z or her W. A Z makes a cockerel. A W makes a pullet.
I’ll admit I had it backwards for years. I figured it worked like it does for us, with the rooster calling it. Turns out he just supplies the Z every time.
That’s the whole thing. What makes it worth knowing for a backyard flock is what else rides on the Z.
Why it matters in the coop: sex-link chicks
Kentucky again: “In addition to determining gender, sex chromosomes carry genes that can affect other traits, such as plumage color. These characteristics have been used in sex-linked crosses and can be used to determine the gender of the offspring.”
Here’s how that plays out with the crosses you’ll see at the feed store:
- Black sex-links. “A common black sex-linked cross is a Barred Plymouth Rock hen mated with a Rhode Island Red or New Hampshire rooster. At hatch, both sexes have black down, but the males can be identified by the white dots on their heads.” The barring gene sits on the Z. A daughter’s only Z comes from her unbarred father. So she grows up solid black. A son gets his mother’s barred Z, and he grows up barred like her.
- Red sex-links. Kentucky gives two examples. White Plymouth Rock hens carrying the silver gene, crossed with New Hampshire roosters, give the Gold Comet. Silver Laced Wyandotte hens crossed with a New Hampshire rooster give the Cinnamon Queen. “The silver gene is on the sex-chromosome and inhibits red pigmentation in feathers.”
- Wing-feather sexing. Same idea, different gene. Hendrix Genetics, which breeds commercial layers, says the gene for fast or slow feathering “is located on the Z chromosome (female chickens have ZW chromosomes, while males have ZZ).” I wrote up how wing-feather sexing works, and why it only works on chicks bred for it.
It only works one way round, which is the part people trip over. Kentucky: “If you mate a Delaware male with a New Hampshire or Rhode Island Red female, all the offspring will have the same Delaware feather pattern.” Swap the parents and every chick looks alike. And “the offspring of a sex-linked cross cannot themselves be used in a second sex-linked cross,” so your sex-link hens and a sex-link rooster won’t give you another batch you can sort at hatch.
What it doesn’t let you do: guess from the egg
Because it’s the hen’s W or Z that decides, some folks figure there must be a clue on the egg. Honestly, I get why. There isn’t one you can see, though. Kentucky: “If the egg is fertile, you can’t determine whether the embryo is male or female.” On the old tricks, it doesn’t mince words: “the chances of being right using these traditional or folk methods are fifty-fifty.” That covers the pointy-egg-means-rooster idea too: “In reality, the shape of the egg is not related to the sex of the offspring, nor does it indicate whether the egg is fertile.”
So when somebody at the feed store sorts eggs by shape before they go under a broody hen, smile and let them. They’ll be right about half the time, which is what fifty-fifty means.
So how do you tell, if it’s not a sex-link?
You wait and you watch. Mississippi State Extension says the signs “can usually be performed after chicks attain 4 to 6 weeks of age,” starting with the comb and wattles. Kentucky says only the males grow saddle feathers, the long narrow ones in front of the tail, and Meyer Hatchery sees those clearly by about 18 weeks. The hen or rooster checker on this site walks through what you can trust at each age.
One more thing the chromosomes explain: a hen lays whether or not there’s a rooster around. He only decides whether an egg is fertile. There’s more on that in laying without a rooster.
Sources
- poultry.extension.org: Sex-Linked Traits in Poultry (Dr. Jacquie Jacob, University of Kentucky): Z and W; the black and red sex-link crosses; one way round only; no second cross.
- poultry.extension.org: Sexing Day-Old Chicks (Dr. Jacquie Jacob, University of Kentucky): no sexing from the egg; folk methods are fifty-fifty; egg shape; saddle feathers.
- Hendrix Genetics: How to feather sex a chicken? (November 2020): the feathering gene on the Z chromosome.
- Mississippi State University Extension: Sexing of day-old chicks: signs readable after 4 to 6 weeks.
- Meyer Hatchery: What to Look for in Determining Gender in Young Chickens (March 2018): hackles and saddles clear by 18 weeks.
Sources checked September 26, 2026. I keep chickens; I’m not a veterinarian.
