Two developing embryos with the same genetic code, such as identical twins, would initially be indistinguishable. They would share the same DNA sequence and would therefore have the same genetic blueprint.

However, the development of an embryo is not solely determined by its genes. Environmental factors play a crucial role, including:

* Uterine environment: The physical environment within the uterus can differ slightly between twins, leading to subtle variations in development.

* Placental sharing: Monozygotic twins can share a placenta or have separate placentas, influencing nutrient and oxygen supply.

* Random factors: Even with identical genes, random events during development can lead to minor differences in cell division and differentiation.

Therefore, while two embryos with the same genetic code will start off looking identical, subtle variations in their environment and development can eventually lead to observable differences. These differences may be subtle, such as a slight difference in height or finger length, or more pronounced, such as different hair color or susceptibility to certain diseases.

It's important to note that even with these variations, identical twins will share a striking resemblance and often have similar personalities and traits. However, their development is not a completely predetermined process, and environmental factors contribute to their individual uniqueness.