All the cells are divided into two when the egg is still in embryo form, then they completely separate and grow and develop. This is why even with identical twins they are never quite exactly the same as the other even though they share the same genetic coding.
The same as when you had the first set of identical twins.
genes
Yes, they have 2 sets of twins, one is fraternal and one is identical. The identical set is John David and Jana.
They have the same set of chromosomes, which can be also stated as having the same set of genes.
Female twins that are not identical are called fraternal twins. Fraternal twins occur when two separate eggs are fertilized by two separate sperm. Maternal twins refer to twins that share the same mother but can include both identical and fraternal twins.
A standard DNA test would rank them as siblings.
Not really.
Yes particularly if your first set of twins are fraternal (aka non-identical twins) as these are the type of twins that are said to have a hereditary connection.
Well, that's an opinion, but as a mother, I've named my first set of identical boy twins Andrew and Aaron, and I've named my second set of identical girl twins Annemarie and Annalise.
I know of two sets of twins, male, where one is straight and the other gay. One set is of identical twins, too. So, in my experience I would say, "not necessarily." On the identical set, the straight one was the first born. It has been my observation that the first born, at least of male identical twins, seems to be the more aggressive one of the two. No scientific basis for any of this - just my observations.
A litter is really just a big set of fraternal multiples. Occasionally there will be actual identical twins. Yes there can be twin kittens.
Identical twins are born when a single fertilized egg splits and develops into two fetuses. Fraternal twins are born when two separate eggs are released and fertilized. Identical twins take a long time to separate within the womb, and sometimes they don't separate entirely (conjoined twins). If doctors observe the two fetuses are connected at any point, that means identical twins. You can also do a DNA test on the amniotic fluid surrounding the fetuses. If there are two sets of DNA present, it means fraternal twins. If there is only one unique set of DNA, it means identical twins.