Which of the following is not same in monozygotic twins
**Core Concept**
Monozygotic twins, also known as identical twins, are formed when a single fertilized egg (zygote) splits and develops into two separate embryos. This results in genetically identical twins who share the same DNA. However, despite their identical genetic makeup, monozygotic twins can still develop differences due to various factors during fetal development.
**Why the Correct Answer is Right**
Monozygotic twins can exhibit differences in their placental development, which can affect the distribution of nutrients and oxygen to each fetus. Additionally, random mutations can occur during fetal development, leading to differences in the twins' epigenetic markers. These factors can result in differences in the twins' physical characteristics, such as differences in birth weight, body mass index (BMI), and even subtle differences in facial features.
**Why Each Wrong Option is Incorrect**
* **Option A:** Monozygotic twins are formed from a single fertilized egg, so they share the same placenta.
* **Option B:** Monozygotic twins have the same DNA, but they can still develop differences due to random mutations and epigenetic changes.
* **Option C:** Monozygotic twins can exhibit differences in their placental development, which can affect the distribution of nutrients and oxygen to each fetus.
**Clinical Pearl / High-Yield Fact**
Monozygotic twins are more likely to develop discordant growth patterns, with one twin being larger or smaller than the other. This is often due to differences in placental development and the distribution of nutrients and oxygen.
**Correct Answer:** D.