4/21 Talk about how twins are born.

The probability can increase if twins run in your family.
* run in one's family: 가족 내력이다.
ex> You should check to see if Alzheimer's disease runs in your family.

Thanks to various forms of fertility treatments, twins can be found more often.
* fertility treatment: 불임치료
ex> There are more and more women receiving fertility treatments every year.

There are two types of twin births: monozygotic and dizygotic.
* monozygotic (=identical) twins: 일란성 쌍둥이
* dizygotic (= fraternal) twins: 이란성 쌍둥이

Identical twins occur when a fertilized egg splits to form two embryos.
* fertilize: 수정하다
ex> Identical twins must feel like they're looking into a mirror when looking at each other.

Fraternal twins result from two separate eggs getting fertilized by two separate sperms.
ex> You can't even tell they're twins because they're fraternal twins.

Because identical twins share the same genetic makeup, they look exactly alike.
* look alike: 비슷해 보인다
ex> I can't believe how much you and your son look exactly alike.


@ There's always a reason for everything.  모든 일에는 이유가 있게 마련이야.
= Everything happens for a reason.

1. Cancer runs in my family.
2. The government offers financial aid for fertility treatments.
3. I have friends who are identical twins.
4. My mother and I look exactly alike.