Yes. Add in environmental differences, such as chemical, nutritional, immune system and so on, gradients in the womb, and different environments after birth. Mutations after cell separation are probably the minor factor for differences, honestly.<quoted text>
Mono-Zygotic twins begin their development from a single split egg and therefore with identical dna, clones of each other. Mutations through development account for the slight differences that can sometimes be observed
I have fraternal twins, not from the same egg and therefore not clones and actually as different as chalk and cheese
For dizogotic twins, environment is what makes them similar, with genes and genetic-environment interaction making them different.
I'm sure you have fun with them!