If you think you're seeing double when you look at two of your feline friend's kittens, there might be a reason for that. While some feline siblings may simply resemble each other, other pairs may indeed be true identical twins. Just as with people and other animals, identical twins are possible in cats, although they're somewhat uncommon.
Siblings Sharing Genetics
While all kitten siblings share some genetic traits with each other, identical twins have the exact same DNA, according to CatChannel.com. These little guys are conceived from the same egg and same sperm from their parents, rather than separate ones. During the mother's pregnancy, this fertilized egg splits and develops into two embryos rather than one, making them literal clones of each other. When the kittens are born, they may share the same placenta, although this is not always the case. It depends on when the split occurs during the pregnancy, advises "Why Do Cats Bury Their Poop?: More Than 200 Feline Facts, Fallacies, and Foibles Revealed."
Mirror Mirror Kitten Images
During development, when the cat mama’s fertilized egg splits into two embryos, the physical characteristics of each cat may "mirror" each other. What this means, is that due to the split, markings that appear on one kitten may appear on the opposite side of the other one. This gives the cats the appearance of a mirrored reflection when they stand in front of each other. Usually mirrored traits appear when the embryo splits between nine and 12 days into a mother cat's pregnancy, according to CatChannel.com. If the split occurs prior to this, the little ones may resemble each other in every way, including their markings, or differ slightly due to cell-splits that occur during their separate development.
Conjoined Identical Twins
In some cases, if a mother cat's fertilized egg begins to split very late in the pregnancy, the two fetuses may not have the time necessary to completely separate from each other and the little ones may end up being conjoined at birth. This means that they will be physically connected by one or more body parts or may even share some of their organs. While sometimes referred to as "Siamese" twins, referring to a set of conjoined human twins from the 1800s, don't confuse these rare identical kittens with the Siamese cat breed. This is a fairly uncommon condition in any breed, which is not often seen in either humans or our feline friends.
Kitten Sibling Genetics and Traits
The only way to truly determine if your kittens are identical twins is to have a vet perform a DNA test on them. Even if your kitty gives birth to only two kittens, this doesn't mean that they are necessarily identical. In fact, kittens from the same litter can have multiple fathers. Because of this possibility and the frequency of multiple births in cats, all kittens are usually considered siblings and not fraternal twins, as would be the case with human twins who are not identical. If your kitty does happen to have identical twin kittens, the twins may resemble each other and share the same DNA, but this doesn't mean that they'll necessarily have the same personalities.