Twins

Among our daily life, Timmy meets several twins,
- his classmates: Ralf & William,
- our neighbour:  Cherish  Cheryl,
- the kindergarten boys: Raynard & Matthew,
- Julian & Julio.

Suddenly he asked me: "Mom, so if it is twins, is it from 2 eggs and 2 sperms?"

Honestly, I don't know the answer, and I told him so.
I had to googled and searched the internet for the answer.

Frankly, I was surprised, how could he asked me that question?
Then I remembered reading him a story about "How babies are made".
But that was quite a long time ago, when his cousin was here.
And we read that story when we were at my mother-in-law's house.
Perhaps that's where he knew the terms about egg and sperm.

I searched the internet and found interesting answers.
Apparently, there are several types of twins:
1. Fraternal / non-identical twins, occurs when two eggs are fertilized by two different sperms.
They may look different from each other, just like siblings.
They may have the same or different gender and may have different blood types.

2. Monozygotic / Identical twins,  occurs when a single egg is fertilized by a sperm, to form a zygote, which then splits to form two separate embryos.    They have the 'mirror image' of each other and  always the same gender.

3.  Half-identical / semi- identical twins,   the very rare form of twinning whereby the twins inherit exactly the same genes from the mother, but different genes from the father.  The exact mechanism of their conception is not well understood, although theoretically occurs in polar body twinning where sperm fertilize the ovum and the second polar body.

Here's the simple summary that I made for Timmy:

Then we talked about how the baby grows when the baby is in the womb.